Topaz is a new project by Gabriele Santilli (this man has working on several REBOL projects).
For the moment at early stage, but it is interresting to follow this project.
And according to TomBon "Topaz is a sillicate based gemstone, with the correct impurities, it could morphe to Topaz Red". Excellent Tom !
The source are available on Github.
And there's also a Try Topaz available online !
Good Luck Gabriele.