GIA Diamond Formation, Mining, and the Diamond Market 2 — Questions and Answers
Question 1: Which mineral is diamond composed of?
- Carbon (Correct answer)
- Silicon
- Boron
- Aluminum oxide
Correct answer: Carbon
Diamond is pure carbon atoms arranged in a crystal lattice structure called the diamond cubic.
Question 2: What is the approximate depth at which most natural diamonds form in the Earth's mantle?
- 100–200 km (Correct answer)
- 10–30 km
- 500–600 km
- 5–10 km
Correct answer: 100–200 km
Natural diamonds crystallize roughly 100–200 km below Earth's surface where extreme pressure and temperature conditions exist.
Question 3: Open-pit diamond mining is best characterized by:
- Excavating a large terraced crater at the surface (Correct answer)
- Drilling horizontal tunnels deep underground
- Dredging riverbeds with suction equipment
- Blasting vertical shafts into kimberlite pipes
Correct answer: Excavating a large terraced crater at the surface
Open-pit (or open-cast) mining removes ore in terraced steps from a large surface excavation, common in early-stage kimberlite mining.
Question 4: Which country is historically the first to have diamonds discovered and mined commercially in the modern era (mid-19th century)?
- South Africa (Correct answer)
- India
- Brazil
- Russia
Correct answer: South Africa
The 1867 discovery of diamonds near the Orange River in South Africa launched the modern diamond mining industry.
Question 5: Alluvial diamond deposits are formed when:
- Erosion transports diamonds from primary sources to riverbeds or beaches (Correct answer)
- Volcanic eruptions deposit diamonds on the surface
- Tectonic uplift exposes kimberlite pipes directly
- Hydrothermal fluids crystallize carbon near the surface
Correct answer: Erosion transports diamonds from primary sources to riverbeds or beaches
Alluvial deposits result from weathering and erosion of primary kimberlite or lamproite, concentrating diamonds in sediment.
Question 6: Which certification program does the GIA administer to grade polished diamonds?
- GIA Diamond Grading Report (Correct answer)
- AGS Platinum Report
- IGI Diamond Dossier
- HRD Antwerp Certificate
Correct answer: GIA Diamond Grading Report
The GIA Diamond Grading Report is the industry-standard document that grades a polished diamond's 4Cs and other characteristics.
Question 7: What role did De Beers play in the 20th-century diamond market?
- It controlled the majority of global rough diamond supply and distribution (Correct answer)
- It exclusively certified gemological laboratories worldwide
- It invented the round brilliant cut diamond
- It set retail diamond prices directly through government contracts
Correct answer: It controlled the majority of global rough diamond supply and distribution
De Beers dominated rough diamond supply through its Central Selling Organisation, controlling up to 80–90% of global rough supply at its peak.
GIA Diamond Formation, Mining, and the Diamond Market 2
Which mineral is diamond composed of?