Fancy Black Diamonds: Natural vs. Treated, Rarity, and Jewelry Value

Fancy black diamonds are diamonds with a saturated, uniform black body color, graded on the GIA Fancy Color scale as "Fancy Black."

Two Origins

Natural (Carbonado / Polycrystalline)

Opaque, porous aggregate of microcrystalline diamond, graphite, amorphous carbon, magnetite. Graphite inclusions absorb all light. Extremely rare; found in Brazil, Central African Republic. Possible extraterrestrial origin (meteoritic). Highest value.

Treated (Irradiated / HPHT)

Off-color (brown/green) natural diamonds → electron beam/neutron irradiation + annealing (800–1200°C) → stable black color. More affordable; disclosed as "treated." Durability unaffected.

Value Factors

• Carat weight (price per carat rises steeply >1 ct for natural).
• Cut quality (affects luster; often rose cut or brilliant).
• Surface blemishes (natural = more inclusions).
• Certification (GIA, IGI) stating origin: natural vs. treated.

Jewelry Use

Bold, modern aesthetic. Men's rings, pendants, accent stones. Often set in white gold/platinum for contrast.