gemstone

Diamond and Sapphire

Carbon (Diamond, C) and Aluminum Oxide (Sapphire, Al2O3)

Diamond has a hardness of 10 on the Mohs scale, adamantine luster, and cubic crystal structure. Sapphire has a hardness of 9, vitreous to adamantine luster, and trigonal crystal structure.

Identified August 3, 2026More gemstone →

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Physical properties

Diamond has a hardness of 10 on the Mohs scale, adamantine luster, and cubic crystal structure. Sapphire has a hardness of 9, vitreous to adamantine luster, and trigonal crystal structure.

Formation & geological history

Diamonds form deep within the Earth's mantle under extreme pressure and temperature, brought to the surface via kimberlite pipes. Sapphires form in metamorphic or igneous rocks like basalts and pegmatites.

Uses & applications

High-end jewelry, industrial cutting and grinding tools, and technological applications.

Geological facts

Diamond is the hardest known natural material on Earth, while sapphire is a variety of corundum known for its deep blue color caused by trace amounts of iron and titanium.

Field identification & locations

Identified by extreme hardness, high refractive index, and distinct crystal or cut facets. Commonly found in jewelry settings.

Other gemstone specimens

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Gemstone Ring

N/A - Set piece of jewelry, likely Amethyst or Garnet with Diamond or CZ

gemstone

Diamond and Gold Jewelry

Carbon (Diamond) / Au (Gold)

gemstone

Ammolite

Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)

mineral

Cubic Zirconia (simulant) or Diamond

ZrO2 (Cubic Zirconia) or C (Diamond)

gemstone

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

sedimentary

Black Opal Ring (Carved Opal)

Hydrated Silicon Dioxide (SiO2·nH2O)

gemstone