I bought a gold/diamond ring in Greece (highly recommended jeweller). The ring is 18ct yellow gold with a 1ct diamond. When I returned to England, an English jeweller confirmed that the ring was genuine.
I now want to sell the ring. Do I need to get the ring hallmarked, is this even possible? If not, how do I prove to a buyer that the ring is what I say it is?
Any advice would be much appreciated!
Thanks

get it appraised at the jewelers.. they will give you a document stating its value

They still might not give you any documents, they may charge you for a full evaluation. It is possible to get a ring hallmarked but it normally costs quite abit. Contact your local Assay office who will be able to help you further as well as a reputable jeweller.

My local assay office in Sheffield are charging me £19 to hallmark my 14k white gold and diamond ring. I just dropped it in today. They test it and the service takes around 3 to 4 working days. It's £30 for a one day service.
It's well worth it as I'm selling it and in my opinion it's a small price to pay if you want to sell it for a reasonable price.
Hope this helps people looking for advice. If you want to advertise unhallmarked jewellery on a well known internet auction site you are warned that it's illegal to sell unhallmarked jewellery. After much research on the internet I discovered it's only illegal for traders (not the average person like me selling a one off ring)
For that reason I decided to get it hallmarked then there'll be no comeback after the sale.

If it is a 1ct diamond then the value is in the diamond. Hallmarking won't add any value as long as it has been tested as 18ct with acid then that is enough for buyers (who can easily re-test it if they wish). What you need to do is get the diamond appraised (you should have been given a certificate anyway when you bought it? ). A 1 ct diamond can be worth £100 or £1000 depending on the 4 C's (http://www.4diamond.com/4Cs/)