my first guess would be that the one on the left is cooked - but maybe that's 'cuz the one on the right is lit better?

but, because i said i'd do this the other day and only just today got around to taking pictures:

this is an Epiphany ring from QVCUK - but it has stones from Chris in it now.
center 8mm, cooked several times, and side 5mm stones in the warmer colour



and the same ring, a bad photo, but it better shows the colour the stones are now: