Gem Stones- Lusture & Dispersion

LUSTRE: The quality of light reflected off the surface of a stone .Use reflected light to judge.
- Metallic: Metal-like the highest possible luster .e.g. Hematite, Pyrite.
- Adamantine: The highest possible luster for gemstone .e.g. Diamond, Zircon, Dermatoid Garnet.
- Vitreous: Glass- like the most common luster for gemstone. E.g. Quartz, Beryl, Topaz.
- Greasy: An oily appearance; common for jade. Also seen in some garnets, peridot etc.
- Resinous: Similar to greasy; used to describe the luster of amber.
- Waxy: Little reflection; similar to the luster of a candle or a fingernail. E.g. Turquoise, Chalcedony.
- Dull: Very irregular, fine- grained surface; common on unpolished, opaque stones. E.g. rough Turquoise, Malachite.
- Silky: Reflection off fibrous structure (sheen), e.g. Tiger’s eye.
- Pearly:Due to structure (sheen); common to Pearl, rough moonstone, cleavage surfaces etc.

Dispersion: The breaking of white light into its component spectral colors.
- Observed as flashes of spectral colors, known as fire.
- A few stones have eye- visible dispersion which can be a useful identifying characteristic.
- The presence or absence of dispersion in diamond stimulants is important in their identification (e.g. strontium- titan ate – very high dispersion, YAG –barely visible dispersion).

Jewelry Designing - Parts of Gem Stone

Different Parts of stones-:
Crown
1.Table
2.Star facet
3.Bezel facet, crown main facet
4.Crown griddle facet
5.Griddle
Pavilion
1.Pavilion main facet
1.Culet
Entire form
1.Crown
2.Pavilion