How to identify Faceted Gemstones

To correctly identify Faceted Gemstones (Cut and polished minerals (e.g., Quartz, Topaz, Zircon, Diamond, etc.)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Highly variable, depending on the specific mineral. Can be colorless (e.g., diamond, some quartz), or exhibit a full spectrum of colors (e.g., sapphire, ruby, emerald, amethyst).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Typically vitreous (glassy) to adamantine (diamond-like), due to polishing. Some may exhibit sub-adamantine or resinous luster.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth and highly polished on the faceted surfaces. The edges of the facets should be sharp and well-defined.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Not applicable to the faceted form itself, as the original crystal form is altered by cutting. The cut shape (e.g., round brilliant, oval, pear, emerald) is a human-designed geometric form.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   The presence and quality of cleavage depend on the original mineral. For example, diamond has perfect octahedral cleavage, while quartz has no cleavage. Cleavage planes can sometimes be observed as internal features or can influence the durability of the cut stone.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Faceted gemstones are not found in a geological environment. Their raw mineral precursors are found in diverse settings: igneous (e.g., diamonds in kimberlite, beryl in pegmatites), metamorphic (e.g., rubies in marble), and sedimentary (e.g., garnets in alluvial deposits).

Key Facts

Hardness

Varies widely, from 6.5-7 on Mohs scale for some garnets to 10 for diamond. This is a critical factor for durability.

Specific Gravity

Varies widely, e.g., Quartz (2.65 g/cm³), Topaz (3.4-3.6 g/cm³), Diamond (3.52 g/cm³), Zircon (3.9-4.7 g/cm³).

Crystal System

Varies depending on the mineral (e.g., Diamond: Isometric; Quartz: Trigonal; Topaz: Orthorhombic; Zircon: Tetragonal).

Color

Extremely diverse, encompassing all colors of the spectrum, as well as colorless.

Luster

Vitreous to adamantine, due to polishing.

Transparency

Typically transparent to translucent, allowing light to pass through and be refracted.

Fracture

Varies depending on the mineral (e.g., conchoidal for quartz, uneven for some garnets).

Cleavage

Varies depending on the mineral (e.g., perfect in diamond, basal in topaz, absent in quartz).

Composition

Varies widely, as faceted gemstones are made from different mineral species (e.g., Diamond: C; Quartz: SiO₂; Topaz: Al₂SiO₄(F,OH)₂; Zircon: ZrSiO₄).

Physical characteristics

• Crystal Habit: Not applicable to the faceted form; refers to the original crystal growth habit of the raw mineral.
• Cleavage Type: Varies by mineral (e.g., perfect, distinct, poor, none).
• Fracture Type: Varies by mineral (e.g., conchoidal, uneven, splintery).
• Tenacity: Varies by mineral (e.g., brittle for most, tough for jade).
• Luster Type: Vitreous, sub-adamantine, adamantine.

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