Where stones are mined, cut and traded.
The ground we search. Mining localities, the cities where rough is cut and polished stones change hands, and the kinds of deposit that put gems within reach.
- Mining localities
- 56
- Trading hubs
- 14
- Countries
- 37
- Deposit types
- 10
Where the
stones come from.
Kimberlite pipes, gem gravels, marble belts and emerald veins. Filter by stone, then pick a locality to read its record.
Locality record
Mogok
- Country
- Myanmar
- Stones
- Ruby, sapphire, spinel, peridot
- Status
- artisanal
- Position
- 22°55′12″ N 096°30′00″ E
The classic ruby district; held by TNLA rebels from July 2024 to October 2025
Positions are approximate, to about 0.1°. Status as of 2026. Chapter 05 · Mining & sourcing
Where stones
change hands.
Most stones are cut and sold far from where they are mined. A search usually runs through several of these cities before it reaches a laboratory.
Hub record
Antwerp
- Country
- Belgium
- Position
- 51°12′36″ N 004°25′12″ E
Rough and polished trading; four of the world’s 27 bourses; 213 million carats shipped in 2025
Hubs are shown at city level. Chapter 06 · Industry & supply chain
From the pit
to the counter.
A stone changes hands many times before anyone wears it. Each stage has its own chapter.
Mining
Exploration, extraction and recovery of rough from kimberlite, alluvial, marine and artisanal sources, then sorting into sales assortments
MiningRough trading
Sale of rough by term contract (sights), tender or auction, and resale of parcels between dealers
IndustryCutting and polishing
Scanning, planning, sawing, bruting and faceting rough into polished stones; about half the rough weight is lost
CuttingPolished trading
Wholesale of loose polished stones, often with laboratory grading reports, through bourses, dealers and online trading platforms
GradingJewelry manufacturing
Designing, casting and setting stones into finished jewelry for brands and retail chains
JewelryRetail
Sale to consumers through chains, independent jewelers, luxury houses and online retailers
Markets
How the ground
holds gems.
Primary deposits keep stones where they formed. Secondary deposits are where rivers and seas carried them. Each asks for a different kind of mining.
Fig. 04.2
Deposit types
| Deposit type | Setting | Stones | Examples |
|---|---|---|---|
| Kimberlite pipe | Volcanic pipes intruding cratons stable since the early Proterozoic; magma generated as deep as 200 to 300 km carries mantle diamonds up | Diamond | Orapa and Karowe (Botswana), Udachnaya (Russia), Diavik and Ekati (Canada) |
| Lamproite pipe | Potassium-rich, magnesium-rich mantle magma forming similar pipes; unlike kimberlite pipes they lack ilmenite | Diamond, including pink and brown | Argyle and Ellendale (Western Australia) |
| Alluvial, placer and marine | Dense, durable minerals concentrated by rivers, beaches and ocean currents after erosion of the source rock | Diamond, sapphire, ruby | Namibian coast and sea floor, Ratnapura and Elahera (Sri Lanka), Ilakaka (Madagascar) |
| Granitic pegmatite | Coarse late-stage granite bodies enriched in incompatible elements; gems grow in open or clay-filled pockets in the core zone | Tourmaline, beryl, spodumene (kunzite), topaz, garnet | Minas Gerais (Brazil), Madagascar, Skardu (Pakistan), San Diego County (US) |
| Marble-hosted metamorphic | Metamorphosed limestone deformed by the collision of India with Asia; ruby grew at about 620 to 670 degrees C and 2.6 to 3.3 kbar | Ruby, spinel | Mogok and Mong Hsu (Myanmar), Luc Yen (Vietnam), Jegdalek (Afghanistan), Hunza (Pakistan) |
| Amphibolite-type metamorphic | Ruby in metamorphosed mafic and ultramafic rocks; most output from colluvial and alluvial ground nearby | Ruby | Montepuez (Mozambique) |
| Basalt-related | Alkali basalts, basanites and related lavas carry corundum xenocrysts up in flows and plugs; gems recovered from the weathered cover | Blue, green and yellow sapphire; ruby | Pailin (Cambodia), Thailand, New South Wales and Queensland, Nigeria, Aksum (Ethiopia) |
| Mafic-hosted (emerald) | Beryllium meets chromium in metamorphosed mafic and ultramafic rocks; about 70% of world emerald production | Emerald | Brazil, Zambia, Russia |
| Hydrothermal in black shale | Evaporite-derived brines at about 300 to 330 degrees C react with organic-rich Lower Cretaceous shale, releasing Be, Cr and V | Emerald | Muzo, Coscuez and La Pita (west), Chivor and Gachala (east), Colombia |
| Sedimentary weathering | Silica concentrated in deeply weathered Cretaceous sandstone and claystone of the Great Artesian Basin | Precious opal (black, white, boulder) | Lightning Ridge and White Cliffs (NSW), Coober Pedy and Andamooka (SA), Queensland |
Fig. 04.1
Section through a kimberlite pipe
- Crater0–0.7 km
Bowl of reworked volcanic debris and sediment. Skinner (2008) gives Class 1 kimberlite craters as 500 to 700 m deep; erosion often removes this zone.
- Diatreme0.7–2 km
Steep body of fragmented kimberlite and wall rock, with slopes near 82 degrees; the main ore body in many mines. Lower boundary is generalized.
- Root zone2–3 km
Irregular intrusive (hypabyssal) kimberlite where volatiles exsolve and fracture the wall rock, starting the pipe. Depths are generalized.
- Feeder dikes3–200 km
Narrow sheets of magma fracturing upward at an estimated 4 to 20 m/s. Kimberlite magma can be generated as deep as 200 to 300 km.
- Diamond source140–250 km
Cratonic mantle above 4 GPa and at 950 to 1400 degrees C, where lithospheric diamonds grew. Superdeep diamonds come from 300 to 800 km.
We search
all of it.
Brief us once. We work the mines, cutters and hubs on this map for you.