Should you buy a diamond with an outdated GIA certificate?

A GIA (Gemological Institute of America) certificate on a diamond should not be 'outdated' unless it contains a market value.

The basics of the stone, the four Cs -- cut, clarity, carat and colour -- will not change over time, unless the stone has been re-cut or irradiated.

If you're unsure of the trustworthiness of a certificate, you can ask GIA to reverify it by its number and carat weight.

Uses the link, below, for this service.