I have in my possession some uncut precious stones, ruby’s, emeralds, sapphires, and I have already had them checked for authenticity. I just want to know where I should sell them? Will a jewelry store buy them?

If you are in a large town check at the university. Go to the geology department. If there is a local gem and mineral society, they should know about it. The odds are very good that is you have a local gem and mineral society there will be at least one person there who facets. That person will be the one who would be interested in purchasing your gems.

I was wondering jewllery that is made in the US with cubic zirconia stones is the jewellery stamped cz. I have been told by someone selling in America that this is the case

I don’t believe that is so. I have never seen it here. but I will check on it.
here is a link that may have some info on it while I look. http://en.wikipedia.org/wiki/Cubic_zirconia

this is the only reference my search came up with….so far.
it says CZ "stamping"…. insted of (Stamped). the wording is suspicious. "stamping" could mean different things. Even sterling silver would say "stamped" as in 925 stamped. not "stamping". So I checked further and saw no info. clearly stating that the CZ stones are stamped with "CZ" to Identifiy Them. So I would not trust it.
http://www.silverjewelrydepot.com/cestsi5mmrob.html

I have CZ jewelry and there are no stamps on them.
I bought them here. I am from the US.

here is another site I found that mentions CZ stamps but says there are none on there cz jewelry.
http://www.ziamond.com/faq.html

after more searching & checking. My answer is still no. that info is not correct.