Advice on price of a pre-owned diamond

[digether]

Hi - I am considering purchasing a pre-owned diamond online with AGS certification from 2008. The owner is actually selling an engagement ring plus wedding band, but seems willing to sell the diamond separately. It is an AGS000 Round Peerless diamond, any idea what % of the original price I should offer to pay? Or what % of a similar unbranded diamond? What else can I do to protect myself while also allowing the seller to protect herself? (How do I get an appraisal without having paid for the diamond already?)

Thanks for your help!

 

[liaerfbv]

I would ask the seller to send it to an independent third party appraiser to take a look at it. Maybe offer that if you end up buying the diamond, she pays for appraisal, but if you do not buy the diamond, you will pay for the appraisal. If you do buy it, the appraiser should be able to ship it to you directly after payment clears to her (via paypal or whatever).

As to price, does she not have an asking price for the stone? It's hard to say without knowing the specs of the diamond what I would offer since I don't think you can automatically say ok since it's used I'll only offer 40% of the value. Different diamonds have a different value on the market and even some second hand stones can command a price premium depending on the specs.