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Record-breaking Discovery of Ruby and Sapphire at the Didy Mine in Madagascar: Investigating the Source

Record-breaking Discovery of Ruby and Sapphire at the Didy Mine in Madagascar: Investigating the Source
By Dr. Adolf Peretti, FGA FGG and Lawrence Hahn, GG
GRS Laboratories (

In May 2012, the GRS lab in Bangkok received two very large, high-quality rough ruby crystals (Fig. 1A) for testing from a client who had flown straight to the lab

from Madagascar.

Fig. 1A, B: A gem-quality rough of over 60 carats from Didy (Madagascar) is faceted into an over 26 carats of magnificent ruby (right). World record prices were paid for such magnificent rubies, initiating an enormous buying rush. All pictures are by the authors Peretti and Hahn and copyrighted by GRS if not otherwise noted. (

The concerned client had heard rumors swirling about in Madagascar that the crystals were synthetic, and that he needed confirmation of their authenticity before his group would proceed with further investments.

Laboratory testing with ED-XRF, FTIR, UV-VIS, Raman and microscope of the specimens confirmed that the huge crystals were indeed natural and unheated. To link these crystals to the mine in question for their client, the authors undertook a perilous field trip to the source of the crystals for a first-hand inspection of the mine site. By documenting the gemstone rush on video and collecting rock and mineral samples from the site for comparison, they would be able to decode the geological conditions under which this corundum deposit was formed.

They would also acquire critical ruby and sapphire samples for further study (Fig. 7A and cover page). Every field trip like this one in Madagascar carries safety risks, logistical challenges and often, delicate negotiation with local residents and the government. Getting there was the first of a series of challenges. As Peretti recalls, “It entailed 12 hours by car to Ambatondrazaka (Amba) followed by a 3-to 5-hour drive to Didy, weather permitting; finally, foot travel for at least a day. Still there was no guarantee of success in this unknown territory in the midst of a seemingly protected and impenetrable rainforest to the north-east of the capital.” Hence, Peretti determined that air travel was the better option, and enlisted a former local gem dealer to arrange for a helicopter flight out of Antananarivo over the apparent national park to locate the mine and plot definitive GPS coordinates. They would determine the nearest landing site, continue to Didy for authorization from the local government for clearance to the destination, and then commence the journey somehow. A 400-liter refueling deposit in Amba was organized by the aviation company. They were accompanied by a helicopter technician in the 12-hour drive to Amba in tandem with their departure from Antananarivo (Fig. 2) 

Fig. 2: A section of the detailed flight map to the mine by helicopter as recorded by our own GPS; 3-4 Good weather flight from Ambohibe to Ambatondrazaka navigated by Peretti when the board computer crashed. (Fig. 5) 4-3 Bad weather flight following terrain to Ambohibe without use of GPS; 3-2 return flight to the capital bypassing the rainforest (1 is the capital Antananarivo).

Excerpts taken from Peretti’s expedition diary reveal the spellbinding drama that unfolded during the field trip.

Monday, May 14, 2012

Late information reached the GRS Laboratory that the mine, with an estimated 30,000 miners, was sealed off for non-locals by the government, and that it is a 3-hour walk from the nearest village. Roadblocks set up by locals or government authorities, heavy rains or adverse road conditions would have compromised our road trip, which requires nearly a 15-hour drive from Antananarivo, known as Tananarive Capital, to Didy the nearest town to the mine. 

3: A memorable snapshot of the authors Peretti (left) and Hahn (right) after
returning from the expedition to the Didy mine. The expedition material
exceeding 150kg that returned back included a portable gem lab and camping
equipment. The authors are barefoot after the strenuous16.5-hour jungle walk to
the mine and back; their feet are sore and the mountain boots are drenched by
mud. (Photo: Cushman. © GRS.)

4A: Granite rocks 10km south of the mines form a mountain range (more resistant
to weathering). (See Fig. 17 for geology).

Fig. 4B: An aerial photo by GRS from the mining camp at Didy (
when overflying the protected forest of Zahamena-Ankeniheny (inserted picture,
Peretti taking over the navigation as onboard GPS computer crashes).

Wednesday, May 16, 2012

Zahamena-Ankeniheny, the forest corridor where the mining was supposedly occurring, is not yet a national park but has been proposed for protection. Referred as a national park, it is earmarked for such classification to prevent its desecration like the protected areas.


Soaring over steep cliffs blanketed by rainforest. The panorama was breathtaking (Fig. 4A). After 40 minutes of flying, the pilot announced that we had reached our GPS coordinates. An assembly of people on the ground came into view (Fig. 4B). The sapphire area called Didy is officially named Ambatovolona.

Circling the mining area following a riverbed, miners were seen digging and washing. Almost everyone on the ground stopped working to stare at the helicopter. A second smaller place we spied suggested that miners were expanding to different areas now. Witnessing hundreds of blue tents, we wondered how many miners were actually there. It did not appear to be a 30,000-miner campsite as previously speculated; but more like 5,000 to 10,000 miners. This was no organized mining effort. It was a first-come, first-served operation led by a large number of individuals.

After circling several times, Peretti signalled the pilot to abandon the area. The images and video footage captured were sufficient, and we did not want to disturb the miners any further. We looked for the closest landing site. Past some small mountains, the mine spanned about 5km to 10km inside the rainforest, and yet, no landing site near the mine seemed possible. Then we spied small groups of cars parked at the forest edge, most likely gemstone buying agents. Then we discovered a small hill with a steep road surrounded by a half dozen houses, like a medieval village fortified on a hilltop. We called it the Eagle’s Nest, and later found out that it’s actually named Ambohibe.

The nearest possible landing site was about an 8-minute flight from the mine next to the Eagle’s Nest. We discovered a harvested rice field with hardened earth and a few cows. We made a test landing there, saving the GPS coordinates for reference. There, we studied the environment before going on to Didy.

Landing at Didy, a throng of charming children met us and a large crowd appeared relatively subdued. They acted respectful and obedient to the local elders. Surely, it was the first time these kids had seen a helicopter. The village mayor explained that all able-bodied men were now mining in the forest, leaving the hard work at the rice paddies to the women, resulting in a low harvest this year. We negotiated an important written permission by the local government to visit the mines.

Then arriving in Ambatondrazaka, a reliable source that had been contacted before the trip offered us a fine lot of small rubies and sapphires for our reference collection. When we examined some large ruby and sapphire specimens using a portable lab (Fig. 24), we realized the mine does exist, and was producing large, unheated vibrant stones. Our anxiety grew as we contemplated being able to make it to the mine. That may be too much to hope for we thought. “Single-day trips to mines are never enough for serious geological field work, and would this mine prove to be a short-lived flash instead of a real rush?” We received a valuable tip, “Buy cigarettes for the miners.” Peretti had recalled that the miners in Ilakaka, working far from civilization, always asked the same question, “Cigarettes?” especially when being photographed or filmed. They expected royalties.

Thursday, May 17, 2012, 8am

FACING A HOSTAGE SITUATION After circling around low clouds, we finally made it to a landing spot. Locals on the ground seemed dangerously hostile, grim-looking folks. They had encircled us and their Land Cruisers had blocked our exit route. A non Malagasy national dealer said, “The local ‘chief’ is asking US$1,000 for landing rights and US$2,000 as passage tax,” disregarding our authorization letter from Didy. We were already there with the helicopter and completely surrounded. We agreed to not comply with their “offer”. Further negotiations reduced the “offer” to US$1,000, breaking the impasse. We started our march from a point we christened the “Car Drop-off;” the furthest point a vehicle could reach (Fig. 5). This parking outpost gathered various 4-wheel drives, crewed by an assembly of local gemstone buying agents. We were met with hostile and sullen stares until they realized we were non-threatening. A driver we prearranged to pick us up there the next day disappeared, never to be seen again.

5: GPS tracking of the walking route through the jungle to the mine, including
the marched elevation profile. Note first steep climb and the crossing of about
14 small mountain peaks (hills) on the way to the mine. Red arrows mark stops
for drinking water and eating in approximate one-hour intervals. Trail inserted
in geological map (Fig. 17)

THE EXPEDITION ON FOOT We commenced our 16-and-a-half-hour walk after programming the coordinates of the mine and this landmark entry point into our GPS. We also took a guide and four porters for our equipment containing tents, food reserves and water, but we carried our camera equipment.
At first, we covered a good distance, moving at about 6km per hour. We gained confidence, following a small stream running through the valley bordering on rice paddies. Further along, the path became more densely overgrown. We crossed two men carrying a massive wooden log, probably rosewood, and walking the opposite direction towards Eagle’s Nest. The log looked like it had been stripped and formed in a factory within the protected rain forest, prepared and hand-carried for exportation. These illegal wood loggers had (probably) also discovered the gems in the first place.

Eugene, the guide, doubled as a bodyguard. Our hired staff needed some energy and prepared themselves by stopping for a rice and fish bowl at a nearby hut. This entry point to the protected rainforest had another group of buying agents that seemed unfit for the brutal walk, relaxing with radios in an improvised hut. We would endure seemingly endless mountain climbing; 200 meters up and down repeatedly. Eugene brought up the rear, ensuring that nobody got lost or injured. The mountain path went up and down, the overall tendency being upwards (Fig. 5 elevation chart).

Fig. 6: A miner in deep mud re-supplying the mine with 30kg to 40kg of rice, oil, small river fish and cigarettes. The miner walked barefoot as regular shoes are stripped off by the deep mud.

Upon returning home and studying the pilot’s logbook, we discovered that 2 hours after leaving the landing spot, the helicopter crew boarded with an unknown person on the aircraft.

The helicopter took off from Ambohibe with instructions to return to Amba, but this time carried an unauthorized blind passenger aboard. The pilot logged everyone by first and last name, except the blind passenger identified by his name “A”. We assumed that the pilot was bribed. According to someone, he was the same ‘chief’ who had previously demanded passage tax. After the entire trip was over, the pilot acknowledged modifying the passenger list and the routing instructions without the financer’s permission. The maverick group overflew the mines, taking pictures and tossing business cards from the helicopter. The unfortunate result of this ill-thought-out activity was that GRS lost exclusivity on documenting the scene, and every dealer operating in the mine was now alerted that foreigners could invade their working space. Those business cards signaled that the mine was about to go mainstream, which increased the risk. Was the crew easily influenced into doing something unethical for business gain?  Were they coerced by A’s influence and nobody wanted to talk about it, or was it an act of favour to “A” to secure a strategic alliance? Most likely the other non-Malagasy nationals had pre-planned this promotional farce to strengthen their buying power.

The helicopter had flown back and forth unnoticed by Peretti and Hahn. So, had the route been carefully chosen to avoid being discovered?

Fig. 7A: A typical example of a 4-carat rough ruby from Didy. It’s not a fragment but a completely preserved rough formed in the rock. Other minerals have formed simultaneously with the ruby and left different types of negative imprints. No signs are found for transportation by a river (no rounded edges and scratches). Blue color zoning in the stone is formed only on the side where it was exposed to interaction with minerals that must have contained titanium. (Hahn Collection).

Fig. 7B: On the left-hand side is an 85-carat rough Padparadscha sapphire that is completely clean and is estimated to exceed US$1 million in value. Another example of a high-value faceted Padparadscha sapphire of 18 carats is shown in face-up and in profile position. This Padparadscha from Didy is loupe-clean, has perfectly mixed orange and pink color, is spared of thermal enhancement and does not show any color-zoning. It is one of the largest faceted magnificent Padparadscha sapphires ever tested.


During the trip, we ultimately shared two-thirds of the rations with the porters and guide who brought no food along. They had a single bottle of water that they shared and refilled in streams (Fig. 8).

Fig. 8: The picture shows a resting point in the middle of the forest about 5 miles from the mine, equipped with a small field kitchen and the local river as drinking source and bathroom. Photo shows Peretti (in red shirt) and the porters carrying the equipment.

In sharp contrast to the white group, they hardly broke a sweat during the walk. They also carried heavier loads; but a lifetime in this searing climate had prepared them.

The terrain was becoming muddier, more overgrown and elevations became steeper; the speed was reduced to 2km per hour airline distance. A couple dozen friendly people crossed our path. We were asked several times if we had been circling with a helicopter. We explained that we were gemologists not journalists, and tourists not buyers. We did not know that they were referring to the helicopter they saw just hours before. Some asked if we wanted to buy stones, but we decided not to buy anything as we thought that showing money should be avoided at all costs. Not buying anything was a tough decision to make, since we were eager to acquire relevant samples from the source. We did not have permission to buy stones anyway, and we did not want to give the impression to Malagasy dealers that we were going to cut them out from their business. Some fellows who made offers were in reality agents who did not intend to sell us stones, but wanted to test us to see whether we were seeking gemstones. We stressed that we were Swiss and German citizens working for a private company. A rumor circulated that American journalists were coming – noticeably not welcome. Local miners and dealers were showing signs of distress over the repeated helicopter visits.

We crossed two rivers and twice accepted our guide’s offer to carry us across, sparing our trousers and shoes from becoming soaked. We were happy with our porters’ offer. They were really onboard with our team after we shared provisions with them, and showed their respect by carrying our heavy equipment.


On the next to last elevation to the mine, we saw the first signs of deserted mining spots with unearthed boulders and holes adjacent to little ponds used for washing.

The weak stream was definitely not in its natural formation, but this was not worrisome. Tropical rain would soon restore the stream’s natural flow. The receding flora would soon flourish. Little hills of washed rock were piled up everywhere with dark round boulders to the size of sand. Obviously a small alluvial riverbed was mined.

Bordered by steep hills, it rapidly became depleted, so miners moved on to easier pickings. The abandoned improvised huts showed that this was not just an exploration site, but had active mining for some time.

The trail narrowed and split into little trails overgrown with roots from the surrounding trees. They were everywhere in the rainforest but were visible here as thousands of miners passed over the surface.

Fig. 9: The mining scene in the upper part of the valley with tents housing six to eight people each, re-supply shops (middle right side), water reservoirs for washing mud, mining sites under the trees and debris dumping places. Damage to nature has been minimal compared to woodlogging activities in the same forest. (S 18 20.31 E 48 33.83, 3486 ft)
Fig. 10: May 17, 2012: The authors Peretti and Hahn found in the middle of the action, two days before the mine was shut down by government authorities and a few months before big investors took over the operation. At this point of the expedition, the authors were agressed. Photo by Eugene (guide).


The entry of the mine was a muddle of tents and makeshift huts on the slopes with countless holes and ditches in the valley. Blue improvised tents hosted up to eight people. We carefully collected this information, to later calculate the number of miners in the area when using aerial surveillance data. We were asked repeatedly, “What are you doing here? Who are you? Were you in the helicopter?” The ones that did inquire about this were distinguished in their dress; not muddy, with shoes, sunglasses and holding torches to inspect gemstones. They wanted to know if we were the competition who would threaten their profit margin.

Many organized miners deliver to agents who provide them with small credits either in cash, tools or food. These agents do not want intruders making counter offers to miners.

Larger stones are routinely brought to the next centers looking for multiple offers and sold to the highest bidder. Obtaining or observing samples directly from the mine is vital, since it is 100 percent proof of its origin. We were able to inspect some rough in the mine and establish absolute proof of the rough’s unique crystal habit.

16:10 Ten minutes into the mine we were still at the entry. The valley widened farther in, where the stream originated. The mine entry had an internal river joining the main stream. The farther we walked, the more miners and housing we saw. We estimated that about 30 percent of those around the mine were actually digging, the rest idling by. Some were women in charge of food and necessities, others were dealers socializing.

Fig. 11: The filming platform from where high-resolution DVD shots were taken for a documentary that was shown at a GRS seminar during the September Hong Kong Jewellery & Gem Fair.


We reached a platform with clusters of mining and washing pits adjacent (Fig. 9, 10, 11 and 12). Each cluster contained three to four people displacing mud from small holes with one person disposing the soil by basket right next to their washing place. We were moving on the slope, as the valley was now impenetrable without disturbing the claims and getting knee-high in mud. We planned to make this expedition more downstream but a security breach required a change. At this point, we were consumed by the mining activity having reached a critical stage in our adventure.

Fig. 12: Miners are digging under the trees to reach a secondary alluvial mining deposit with boulders of gneiss, amphibolite, gabbro and quartzite.

It was like the California gold rush that prospectors encountered a century ago. This time, it was for the largest sapphires and rubies ever unearthed (Fig. 14 and 16).


We found ‘actors’ here who demanded that their pictures be taken. One such show-off swung a thick wooden stick, shouting in Malagasy at miners on the other side, as if he were the King of the Mines. Some people, probably neighbors from Didy, approached. Suddenly, everyone was looking in one direction as shouting escalated. We saw no carbonate rocks on this visit. It was too risky getting closer to pick up samples. We did this later at an abandoned mining spot.


A highly intoxicated miner approached Hahn, chattering nonsensically in French. He was trying to explain that Malagasy people were poor, expecting a handout and calling us American journalists. The drunk persisted, he was dissatisfied with the attention received. He slapped away Peretti’s video camera. Eugene intervened. This drunk had converted his small liquor bottle into a weapon with Eugene and the miner facing off in Malagasy. A crowd gathered round, and we did not expect them to take our side. Our own porters were frozen in fear, watching helplessly. Eugene commanded the drunken miner to back away, warning him about consequences. He was stunned by the harsh presence of our bodyguard, but resumed his threats. The drunk began shouting across the mining site to the other slope saying, “Americans,” and agitating them to incite riot by falsifying our intentions and mobilizing them to his side. We had to leave the site now. People were still not fully convinced that we were not the American journalists threatening their mining efforts. Our original plan to camp close to the mine was no longer realistic. Getting as far away as possible from the site became our objective. Eugene looked at us with his typical smile; we smiled too, simulating confidence. The three porters followed silently as they had the entire trip. They did their job well, but our real safety line proved to be Eugene’s bravado. Fortunately, Eugene’s head-cam captured some of the most interesting footage.


Fig. 13: A 40-carat GRS-type “Royal Blue” rough sapphire from Didy (Madagascar) that can be cut to a 10- to 20-carat gemstone. Estimated wholesale value exceeds US$100,000. Note that this is not a crystal fragment but the sapphire’s original shape without crystal terminations as grown in the mother rock.

While exciting, our “King of the Mine” reappeared proudly showing a sapphire rough weighing approximately 10 carats (see cover photo). It lacked fine color and was worth no more than US$200. What was very interesting was that the crystal exhibited no growth phases nor showed habit. He had broken his posturing to the others and his air of dominance may mean that a US$200-stone actually was a big deal. We could not imagine the outcome had we shown him money and made an offer on the stone. Hahn had kept him on our side by letting him feel admired for his low-value sapphire.

On return, we noticed the pervasive blue tents, with some sitting atop deep pits. An entire village of over 50 tents camped under the trees with improvised shops and gambling platforms with six to eight people inside a single tent. Some huts were double-layered with a professional tent inside covered by a larger one, as a shield against the heavy rain. Some tents covered a mining pit protecting a deep cylindrical hole into the ground.

Fig. 14: At the washing place, we encounter a woman washing, probably from Didy. Her child should be at school. He is most probably searching for platinum and not gold but may not be aware of it (Platinum occurrence See Fig. 17).

Fig. 15: Miners digging deeper into the alluvial bed to reach the gem-bearing layers. These layers are carried away with baskets to the washing place.

Fig. 16: Two strong Malagasy men washing a heavy load of soil that exposes large pebbles from the alluvial bed mostly composed of gneiss, amphibolites and gabbros, but no carbonates.


We were determined to walk until dark by using flashlights for another hour and perhaps throughout the entire night. Possibly some miners might be organizing an ambush to rob us along the way back, so moving fast was our best option.
17:20 We reached the deserted mining place; our last chance to examine and collect rock samples. The porters and Eugene exchanged views on what had just transpired. Finally Peretti could commence his fieldwork (Fig. 20). With a small hammer he began examining rock samples from the alluvial riverbed. Soon, different types of rocks were identified, like a mica-gneiss, amphibolites, gabbros and quartz boulders. He knew that sapphire often forms in geological systems that produce radioactive minerals, like thorianite-uraninite, zircon or ekanite, which can also be radioactive. So a Geiger counter was brought along. A very slow and systematic scan of smaller pebbles in the waste pile of the mine revealed very highly radioactive minerals after an area of only 40cm2 by 40cm2 was searched. The scale measured out-of-limit and its beeping sound attracted the rest of the crew. A large crystal was retrieved for later lab analysis. Hahn and Eugene joined the search attentive to the Geiger counter beeps becoming more intense the closer they got to a specimen. The measurable radioactivity radius with our device was only of 15cm diameter distance (B- and minor Y-rays). It took only 2 minutes to find another sample. 5kg of rock samples were packed and brought back to the laboratory. (Fig. 19)
Fig. 17: A map showing the “Geology Dreamland” for the Didy (Madagascar) mine. The mine is situated in the metamorphic rock suite of gneiss, amphibolite, quartzite, intercalated sillimanitegneiss (complex of Mananpotsy), migmatites garnet and biotitebearing ortho-amphibolite. The gem-bearing zone is mirrored in the West (approx. 48.50E) with a large intermediate zone of gneiss and amphibolite of the Beforona group and even large bodies of gabbro are found (48.45E and 18.37S). The main difference in the rocks at the mine itself is the presence of Nb-Ta mineralization. As the map shows, this indicates the presence of pegmatite. The Ambalavao rock suite surrounds the mining area and contains quite different rock types including anatectic granites and migmatites. They are partially melted rocks typical for a lower high-metamorphic continental crust. The sillimanite gneisses of Manatopsy corroborate the high grade of metamorphism of this area (high-temperature). The rock types that were predicted by the map (amphibolite, gneiss and quartz) were indeed found in the mining area (Fig.19). Signs for hydrothermal activity were also discovered (most probably in connection with an intrusion) by abundant Fe-Th-Pb-Bi-Zr-Ta-U-Y-Nb-oxide mineral occurrences (Fig. 20). Note: the expedition trail in the map and the location of studied outcrop (Fig. 18). The possible scenario of sapphire and ruby formation is different to that in Adranondambo (Madagascar) and Winza (Tanzania) (See Lit.1, 4) and may be related to fluids and/or melts deriving from plutonites and the metamorphism of Si-under saturated and Al-rich rocks at high metamorphic degrees. Because of the large-scale mapping (1 to 500,000), further small-scale geological studies are necessary for further clarification. The Mine location was added from our GPS data collected, and river systems potentially containing gems are indicated with names. Legend selectively edited and translated into English from French. Map cropped from Carte M?tallog?nique et de Pr?diction des Gisments, M?taux de Base et M?taux Pr?cieux, Feuille No 6-Toamasina (See Lit. 3).


19:00 Hahn assisted by Eugene quickly set up camp with a professional 2-layer mountain tent and high-tech mosquito nets, and cleared rocks and sticks to level the ground. The torches attracted mosquitoes and flying insects. Humidity emanating from trees creates its own ecosystem in rainforests. The cold nights make rain inevitable. The porters took out their equipment and built a camp with a small sheet of plastic connected between trees offering some protection against the rain. That night, they placed sheets above the mosquito nets but it covered only about 60 percent of the area.

Friday, May 18, 2012


Around midnight, a downpour started and the schedule needed to change. We decided to be up by 4am. The rain would have made the muddy trail hazardous. Peretti contracted some radiation exposure due to mistakenly using his backpack as a pillow containing the radioactive sample. Thankfully, no contamination occurred since the samples were sealed.

6am Like the flick of a switch, the darkness was replaced by light. It was an amazing event. The misty fog from last night’s rain hovered over the hills. Majestic trees of stunning beauty dominated the scenery in this natural wonderland in Madagascar. It was an amazing sight. The area overlooked the place where the largest rubies and sapphires in the world were found – a paradise of exotic fauna and flora accompanied by calls of lemurs and rare birds.


Stunned by the wildly diverse and colorful rock formations (Fig. 18A/B) Peretti took dip and angles of gneiss formations and gathered rock samples. Several places on the trail bore signs of small mining activities, signaling that the miners identified this as mother-rock bearing sapphire or ruby. The rock formations were complex layered rocks with different chemistry; with some layers containing amphibole of pyroxene pockets but they were deeply weathered with no fresh specimens available. Interesting boudinage was seen in the rocks’ layers. These lenses showed an increase of grain size, and promising to the formation of larger sapphires. The exact position of these rocks was recorded on the integrated handheld GPS, and the integrated GPS in the video camera producing valuable footage.

Fig. 18A: An outcrop several miles away from the mine on the hillside (marked in Fig. 5) exposes an extremely tectonized and stretched rock suite with a very inhomogeneous chemical composition shown by its weathered colors. Apart from a few minerals such as probably pyroxene or amphibole (see finger pointing), only quartz layers have survived the deep weathering.
Fig. 18B: The inserted picture shows a strong boudinage of the rocks during tectonics in certain areas with an increase in grain size. Such local occurrence in the rocks would be beneficial and necessary if the rubies and sapphires are formed by metamorphism. Miners did attempt mining at this spot and it seems their experience made them conclude it was not worth the effort.

Fig. 19: Amphibolites and gneiss rocks that were found in the riverbeds of the mines are shown. The rock-type was predicted by the geological mapping (Fig.17) and is a potential good culprit in the general scenario of sapphire and ruby formation. It is only part of the alluvial layer; a primary rock formation containing the gems was not exposed. (GRS Rock Collection.)


8am Increasingly, miners and villagers passed us on their way to the mine (Fig. 6). While we were walking out, they were going in with new supplies. They used sticks and metal poles to suspend rice sacks filled with rice, cooking oil, medicine and cigarettes. We could also estimate the population at the mine by calculating the food supplies being brought in. We interviewed the porters on the contents of their load. Then we created a formula based on 5,000 calories of daily consumption per person. By counting the number of porters and inquiring about their cargo, we estimated that approximately 450 people transported 2 tons of consumables including a live cow to the mine daily. There were likely 5,000 to 10,000 miners at the mine.

The average load was between 20kg to 40kg per porter. We were later informed that a pack of rice sells for US$30 at the mine, three times the regular price. People at the mine were not only chasing their dreams, they were making substantial personal investments. Thinking back, we estimated only about 30 people leaving the mine the day before. Only dealers questioned us when we left. A group of 20 to 30 influx miners told our porters they heard the day before that the mine is going to be closed by foreigners, a disturbing forecast. We assured them that we were not interested in shutting them down. Hahn explained in French that like them, our business depends on mining activity.


10:20 Arriving in Antananarivo after a one-hour helicopter flight (Fig. 3), Hahn asked the pilot to hold up the flight log “la fiche de vol” so he could take a picture, otherwise we would have never discovered the rogue helicopter trip. Peretti paid US$2,000 surcharge for the extra kilometers flown, most of which were non-authorized.


A driver drove us out of the heliport compound and stopped after the window suddenly exploded from the middle out. The right rear window had burst into tiny glass bits just 20cm from Peretti’s head. Hahn ordered the driver to leave immediately, thinking they were being ambushed with some type of projectile. The heliport was alerted and the police apprehended a disturbed woman within 30 minutes caught throwing stones. We thought this incident was resolved way too fast and was most likely a fabrication. The person or the object should have been noticed, so it had to be fired from far outside our line of vision, and was never recovered. Peretti could not move for the rest of the ride to the hotel because of the glass shards covering his neck and arms.

Our phones kept on ringing. Someone wanted us to test a large stone while another wanted money. With no stones to be exported except reference specimens (Fig. 26A-D), we boarded our flight to Bangkok. Passing the boarding checkpoint, Hahn was singled out by customs for a random bag search along with four individuals who appeared to be from mainland China. Hahn told the customs officers that it was not necessary to search and make a mess out of his stuff.  Miraculously, it worked.

Fig. 20: Peretti examines the leftover gravel of a mining site with a Geiger counter and discovers highly radioactive minerals (Fe-Th-Pb-Bi-Zr-Ta-U-Y-Nb-oxide mineral).

Fig. 21: A set of eight highly valuable faceted rubies ranging from 7 to more than 14 carats in size in the hand of one of the authors (AP) exceeding an estimated market value of US$10 million. Two of the stones over 10 carats were classified as reminiscent to GRS-type “Pigeon Blood” color category. The Didy (Madagascar) rubies made an overnight appearance to become some of the world’s largest rubies unearthed so far, competing in beauty and rarity with the finest Burmese rubies.

Fig. 22: A closer look of an over 7-carat ruby from Didy (Madagascar) demonstrating complete absence of eye-visible inclusions. These rubies from Didy lack silk nests that would potentially disturb the clarity of a stone by producing eye visible whitish reflections. The rubies are so clean that synthetics are easily smuggled into the lots at the mines. (Photo: W. Bieri. © GRS.)


Two days later, mining police moved into Ambatondrazaka and the non Malagasy dealers closed their buying operations, temporarily retreating to the capital for a few days. With the mining area also raided, the miners cleared out. The miners and dealers have gone back by now or relocated to slightly different areas in the forest.

Some passengers traveling with our helicopter were investigated for an unauthorized helicopter trip, and petitioned Peretti for a copy of his authorization. Peretti sent the documents to resolve the matter, but he was not aware that an investigation was ongoing regarding the dissemination of business cards and illegal solicitation in an unauthorized mining site. The man whose name was on the card was imprisoned and had to put up considerable bail. The matter as to how GRS would be compensated for the air hijacking during the expedition is still unresolved.


At the June Hong Kong Jewellery & Gem Fair, news reached us that a dealer sold a 7-carat vivid red ruby (Didy) for US$1million (Fig. 14). These rubies were true record-breaking treasures of nature. GRS was the only company in the trade that witnessed the activities in this mine firsthand.


GRS hosted a seminar, “New World Record Pigeon’s Blood Rubies Discovered,” during the September Hong Kong Jewellery and Gem Fair.  The new findings were presented at the said event. (see – keyword: GRS)

Fig. 23: A set of sapphires from Didy (Madagascar) ranging from 5 to over 10 carats with the typical GRS-type “Royal Blue” colors normally found solely in sapphires from Sri Lanka, Burma and Ilakaka. (Madagascar). (Photo: W. Bieri. © GRS.)

Fig. 24: Peretti works with a portable microscope to search through lots of rubies and sapphires of dealers in Ambatondrazaka. The presence of illmenite, zircon clusters, blue color zones and absence of silk make these rubies very easily distinguishable through microscopical examination from all other ruby localities, even from the counterparts found in Winza (Tanzania). The same is true for the sapphires that contain large negative crystals accompanied by secondary fluid feathers, isolated zircon crystals, black illmenite inclusions, oriented pargasite needles and the general absence of silk (Lit. 2).


The following information was received from the gemstone market: A major investor (GF) has taken the mining rights in the upper part of the valley and a private investment group involving non-Malagasy nationals has secured the mining rights in the lower part of the valley. Both are hiring locals from Didy for the work at the mine.

The investment group currently has at least two agents in the forest supervising the operation. Additional wild mining must be taking place since a 128-carat rough sapphire had been submitted to GRS from outside these two mining operations. Submissions of stones originating from Didy to the lab have also resumed.

Fig. 25: Statistics of 25 rubies from Didy (Madagascar) tested by GRS just three months after the rubies were discovered. It shows that after only a short period of time two magnificent rubies over 20 carats appeared. Such large rubies are usually the positive by-products from decades of mining in large areas such as Mogok (Burma, Myanmar). Statistics by GRS.

Fig. 26A: A large negative crystal with a secondary fluid inclusion feathers. This is one of the hallmarks of Didy sapphires. Abundant silk typical of Burmese and Sri Lankan sapphires is absent.

Fig. 26B: Mica, ilmenite and zircon inclusions are found in a Didy sapphire of over 5 carats. (GRS Collection.) These minerals are common in amphibolite-gneiss rock suites found at the mine. Ilmenite was confirmed by GRS using SEM-EDS analysis in July 2012. (M. Meier, SEMlaboratory, Geoscience, University Fribourg, Switzerland)

Fig. 26C: Pargasite needles are grown from fluid inclusion voids and have penetrated the entire sapphire in orientation. This is the first time one of the authors (AP) has seen such a phenomena in a sapphire and it shows that the sapphire was grown in a dramatic hydrothermal event. Color zoning is also present in this sapphire and the zoning discontinues irregularly. No whitish milky zones are present such as in other sapphires from Madagascar.

Fig. 26D: A folded feather within a faceted ruby from Didy (Madagascar). Such features are normally expected in sapphires and not in rubies. (Inclusion Photos: W.Bieri & A.Peretti. © GRS.)

Lit 1 Adolf Peretti, Francesca Peretti, Anong Kanpraphai, Willy Bieri, Kathrin Hametner and Detlef G?nther. Winza Rubies Identified. Contributions to Gemology (2008), 7-97 pp.
Lit 2 Adolf Peretti, Willy Bieri, Kathrin Hametner, Lawrence Hahn and Detlef G?nther (2013). World-record rubies and sapphires from Didy (Madagascar) and the new sapphire mines from Kataragama (Sri Lanka). Expedition Report, Geology and Gemology. Contributions to Gemology, No. 12, in print.
Lit 3 Carte M?tallog?nique et de Pr?diction des Gisments, M?taux de Base et M?taux Pr?cieux, Feuille No 6-Toamasina (2008) (J. Ramarolahy, D. Rakotomanana, B. Moine, E. Ortega, L. Chevallier, F. Hartzer, G. S. de Kock, S. W. Strauss et, A. F. Randriamanantenasoa, J. Naden, L. Noakes, Edit?e par: British Geological Survey Keyworth, Nottingham, UK) MINIST?RE DE ??NERGIE ET DES MINES Project de Gouvernance des Ressources Min?rales (PGRM).
Lit 4 Edward G?belin and Adolf Peretti (1997): Sapphires from Adranondambo mine in SE Madagascar: evidence for metasomatic skarn formation. Journal of Gemmology, Vol. 25, No. 7., pp. 453 – 470.
Lit 5 Jewellery News Asia – Show Daily, 24th Sept. 2012, page 10.

GRS would like to thank the Y. Group for making us discover Didy while providing infrastructure and hospitality on the ground; Tom Cushman for the strategic planning of governmental and local passage permissions, and organizing transportation and data; the Government of Madagascar and the Mayor of Didy for passage permission and providing local support; Gem Paradise and friends for sourcing opportunities; all local miners; Assist Aviation; Ghambi; Diana Jarrett; and most of all, our porters who did an amazing job together with Eugene who might just have saved our lives. And last but not least, the amazing GRS team for holding the fortress at the peak of the laboratory workload. For the Chinese translation of the article (traditional and simplified) please visit