Thursday Challenge—"hard"

I understand they've now found some things that are
harder than a diamond—but surely not as pretty.
I inherited this stone from my wonderful
mother-in-law, but had it taken out of 
an old-fashioned silver setting and remounted
by a jeweler in Florence, Italy—where
they know a thing or two about gold.
(I think my MIL would love it.)

[To see more of the Thursday Photo
Challenge, visit Dale's meme.]