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Hot rocks

Rogerson gives us
a primer on colored
stones:

Rubies and sapphires:
"If the mineral corundum
goes toward red, it's a ruby.
If it goes toward any other
color it's a sapphire. The
Burmese ruby is the top of
the line. In sapphires, the
so-called Ceylon (from Sri
Lanka) is the most
desirable".

Emeralds: "The best
of these green jewels
come from Colombia.
For verification, have
an expert check to see
if the stone appears
pinkish when viewed
using a "Chelsea filter."

Heated vs. unheated:
"Most corundum is heated
to intensify the color.
Unheated corundum
stones are very rare,
and therefore costly.
They should come with
certification from the AGTA
or another internationally
recognized lab."

Beryllium-treated or
diffused (artificially
colored) stones:
"This process changes
the color of rubies and
sapphires. Beryllium-
treated corundum sells
for a fraction of the price
of its natural or heated
counterparts."