Jewelry

[depglass]

I have several rubies and none of them have degraded over time.  You have to assume all are glass filled unless you spent thousands for the stone. 

My only advice would be to follow the directions on jewelry cleaners that you might purchase for any jewelry.  Don't soak longer than stated, I once loosened all the stones in a Weiss costume piece I inherited.  I ruined a Valitutti beautiful Ethiopian opal by mistakenly leaving it in a soap type cleaner for a month.  Gold and silver?  I also ruined a pair of gold earrings and came to the conclusion there was a coating of some sort on them.  Live and learn.

[gertrudecloset]

Not all gemstones will have the same sparkle as the next.  Perspective.  Don't expect a quartz stone to sparkle like a Zircon.  It won't.  Don't expect a Saphhire to sparkle like a Sphene (it won't).  Not even all diamonds "sparkle."  That depends on the color and inclusions.  Learn what to expect from the gems you purchase so that later you are not sorry you purchased them @qualitygal 

A lot of gemstones are indeed treated.  Depending on which stone and how it was treated, some treatments last forever, some don't.  You have to just know something about the stone before you buy it.  There are some gemstones that are never treated and come out of the ground with the brilliant color you see before it is faceted.

There is a hardness and refractive index anyone can use to get an idea of a stone's sparkle or the lack of because of the stone itself.  Having nothing to do with treatment.