How is Topaz Obtained?

Prospecting and Mining

The ground is prospected. When deposits are found then the process of digging begins. Topaz is usually mined using the surface mining method, as with an open pit mine. Underground mining is also used. How deep the deposit is determines which type of mining to use.

Color Treatments: Radiation, Heat, Coating and Diffusion

To produce man-made blue topaz, topazes are irradiated. There are several kinds of radiation including low energy gamma rays, and electron and neutron radiation. The European standard of irradiation is less than 2 nCi/gram and the American standard is less than 1 nCi/gram.

Rays such as low energy gamma rays usually don't produce radio-isotopes. The color produced from these waves isn't as strong and tends to be unstable.

Neutron and electron radiation treatments tend to be more radioactive. Companies that work with the neutron treatments keep the treated gemstones in secure storage rooms in order for the radiation to wear off.

To obtain a sky blue color, topazes are sometimes heat treated. Other treatments involve either coating the topaz with a thin film of colorant, or coating the topaz with a chemical and heating it, a process called diffusion.

Synthetics and Imitation

Synthetic topaz is manufactured from an easy to oxidize silicon, aluminum and fluorine compound. This compound is sent through a flame oxidation burner. The particles that result from being passed through the burner are sintered (bonded and partly fused using pressure and heat) into an complete formation.

Imitation topaz is made by changing the appearance of a material to look like topaz. Common materials used to make imitation topaz are citrine (a yellow variety of quartz) and glass.

Resources

• Topaz Mineral Data