I have a ring with a 10 carat natural emerald in. it is very near flawless and is an attractive deep green?

Question

do you know its value? how rare is it?

Answer 1

I think a jeweller may be best to answer that. You can take it to a jewellery store & get the wt and value estimated.

Answer 2

If it is as you describe, it could be very valuable = thousands of dollars.

But it's hard to know just from words.  You need pictures.

The site below has pictures of many different emeralds: different color shades, clarity levels, etc. and it says how valuable each one is.

You can compare the emerald you have to those pictures.