- Color: blue, yellow, pink, red, brown, green, colorless
- Hardness: 8
- Refractive index: 1.60 - 1.64
- Density: 3.50 - 3.58
- Chemical composition: Al2[SiO4](F,OH)2
- Crystal structure: orthorhombic
- Origins: Brazil, Madagascar, Russia, USA, Mexico, Pakistan.
The most valued color for a topaz is orangey-pink (an example being the imperial topaz from Brazil). Heat treatment is common for yellowish stones, with light blue or colorless stones being subjected to x-ray treatment and heating. Very big, clean crystals are common. Topaz prices subject to noticeable variation due to fashion trends on local markets.