Danburite comes from Danbury, a city in Connecticut, USA.

In the British Museum of Natural History in London, England, there is a group of yellow sai citrines from Myanmar, weighing about 139 carats; and another group of yellow sai citrines, weighing about 18.5 carats, from Myanmar is also collected in the Smith Museum in Washington, USA. Topaz. The inscription name of Sai Huangjing is only because its composition is very similar to Huang Jing, but after all, it is slightly different, so the Chinese translation is Sai Huangjing. Most importantly, gem-quality topaz is hailed as a substitute for diamonds in collectors, also because gem-quality topaz is very rare. Topaz comes in transparent, pink, yellow, and lavender colors (some topaz has stripes). In fact, most topaz is opaque, and the transparent part is very rare. There are very few raw ores of transparent topaz that can reach the gem level, and the ore itself is very, very small, so gem-quality topaz can only be made into finished products such as rings and pendants.
For lovers of Sai Topaz, Sai Topaz is largely used as a collectible rather than made into jewelry. Maintaining its original appearance is also an obsession of many collectors.

Natural chemical composition: CaB2SiO42
Color: colorless, light yellow, yellow, pink
Color: high crystal transparent
Crystal system properties: orthorhombic
Hardness: 7
Specific gravity: 3
Refractive Index: 1.630 – 1.636
Polygonal Refractive Index: 0.006 (stable)
Dispersion: 0.017 (low)
Absorption spectrum: Blue and green apatite are mixed absorption spectra for rare earth elements
Luminescence: Under long and short-wave ultraviolet light, it can emit blue light color