Charles Sweigart of Reinholds, Pennsylvania adds this information on Topaz & Amber gemstones.

I can add no input into the glass color differences, but one should not try to compare glass color names to the natural materials Amber is found in many different natural colors. It is also found ranging from transparent to translucent to opaque. Topaz gems are also found in many colors including colorless, though the example shown is the most often sought after for jewelry, but even blue is often used and is the Texas state gemstone.