Seylan Gems & Jewelry
Opal is valued for play of color: flashes that move as the stone turns. Body tone, the pattern of those flashes, and whether the stone is solid or assembled all change the price. Hardness numbers understate how careful you need to be.
Specifications
Typical published ranges used in gemology. Specific gravity below matches our carat calculator default where applicable. (SG 2.15)
| Hardness (Mohs) | About 5.5–6.5 |
|---|---|
| Specific gravity | About 2.15, and it varies with water |
| Optic character | Singly refractive, often hazy |
| Composition | Hydrated silica |
| What you judge | Play of color, body tone, pattern, and stability |
| Lustre | Vitreous to resinous |
A stone with several colors, moving across the face, is a different object from a stone with one small flash in the corner. Dark body tone can make the colors look stronger. Light body tone is not a defect by itself. Look at the face, not a cropped sparkle.
A doublet or triplet has a thin opal layer on a backing. It can be beautiful and it must be named. We will not describe an assembled stone as a solid opal.
Opal can craze if it is dried out, heated, or knocked. Do not steam it. Do not leave it on a dashboard. A ring needs a setting that shields the edge. If you want a stone you can forget on your hand, sapphire is the more forgiving choice. If you want play of color, accept the care.
Yes. It is hydrated silica. Sudden heat or a very dry environment can damage some stones. Care is part of owning one.
No. Diamond fire is dispersion from the facet pattern. Opal’s color comes from the way the silica spheres diffract light. The care and the mineral are different.
Ready to look
Browse certified stones estimate carat from millimetres or ask us to help interpret a report.
Join collectors who shop certified Ceylon stones with real 360° views. Code emailed instantly.
No spam. Unsubscribe anytime. One code per customer.
Enter your email. If you leave, we will send this cart back — Ceylon gems often sell as unique pieces.
Sapphire
Ruby
Alexandrite
Emerald
Padparadscha
Aquamarine
Spinel
Garnet
Peridot
Tourmaline
Tanzanite
Citrine
Quartz
Chrysoberyl
Apatite
Topaz
Amethyst
Lolite
Zircon
Sinhalite
Cats Eye
Opal