Seylan Gems & Jewelry
Alexandrite is chrysoberyl that changes color with the light. A fine shift is green to green-blue in daylight and red to purple-red in warm indoor light. A weak shift, or a change that only appears under a special lamp, is a different purchase.
Specifications
Typical published ranges used in gemology. Specific gravity below matches our carat calculator default where applicable. (SG 3.73)
| Hardness (Mohs) | 8.5 |
|---|---|
| Refractive index | About 1.746–1.755 |
| Specific gravity | About 3.73 |
| Chemistry | BeAl₂O₄ — chrysoberyl, colored by chromium |
| Pleochroism | Strong; the color change is a separate effect from pleochroism |
| Lustre | Vitreous |
Ask what the stone does in daylight and under an ordinary warm lamp, not only under a jeweler’s LED. Photos taken in one light will favor one side of the change. If we have more than one photo, compare them. If we have a 360 view, pause it and look at the face, then remember that the screen’s white balance is not daylight.
Color-change sapphire and color-change garnet exist. The name alexandrite belongs to chrysoberyl. If a listing uses the name, the species should be chrysoberyl, not “alexandrite-like.”
Fine color change in a large stone is uncommon, so carat weight and the strength of the shift are priced together. Do not ignore a muddy in-between color. Some stones look attractive in each light and dull in mixed light, which is how they will be worn.
Hardness 8.5 is suitable for a ring if the setting protects the girdle. Chrysoberyl can show twinning and silk. Those features can support a natural identification. They are not a guarantee, and a photo of them is not a certificate.
Estimate weight with the alexandrite specific-gravity default only as a check against the listed carat and the millimetre size. Then read the product text for treatment. Most alexandrite in the market is described as unheated, but the sentence that matters is the one on that item.
If you want help comparing two shifts, book a consult and tell us which lights you care about. We will talk about the stones we have. We will not promise a color change we have not seen.
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