I`m looking for a 3/4 to 1 carat round tanzanite stone to replace one I lost ( it wasn`t insured sadly ). Would anyone have any places / locations or advise they know of where I could find one for a good price. THANKS

I would look first at Rio Grande (riogrande.com). They have a wide array of different precious stones at different sizes.

eBay. They have everything.

I would go to a local jewelry store, or the one where you got the ring. I lost a diamond in my ring and went back to the store I bought it from, they replaced it super cheap. You never really know what you are getting if you buy online.