Amber is generally treated by baking it at approximately 350’ F.
to the desired color. Some of it does occur in the darker
colors. Copal is much softer than amber and in my opinion should
be avoided for anything except specimen purposes. Copal will
melt at about 350 degrees - it was once used to line tin cans.
Amber can be polished in the setting if you goof(mildly) and
scratch it - I wouldn’t try it with Copal.