zircon

A mineral occurring in many different colours and which, in its translucent or transparent forms, is used a gemstone. The colourless form is sometimes used as a substitute for diamond.

A colourless, pale yellow, or smoky zircon may be called a jargon or jargoon.

A red, brown or yellow zircon may be called a jacinth or hyacinth.

Zircon is one of the alternative birthstones for those born in December.