I hv 200 year old rare gem..where to evaluvate it in india,,or world?

Gem stones are millions of years old not hundreds. If you mean you have a piece of jewelry with a gem stone in it that is very old then take it to a jewellers to get it appraised. if you just have a gem stone then also take it to a jewellers and get it appraised but I warn you now the "age" of the gem will have no bearing on its price.