I am interested in a diamond that is EGL certified. Is that something to worry about? If I wanted to make GIA certification a condition of the sale, how long does the process take? I want to gauge how reasonable this request is. Just wondering. Thanks.
Short answers: EGL-USA has proven reliable of late (be sure it is the USA division). Certifying a stone with GIA costs in the neighborhood of $200.
Longer answer: Here is a link to a diamond grading lab survey conducted by Leonid and Garry Holloway. Very pertinent information which could give you a better feel for EGL-USA as they relate to GIA and AGS.
The jeweler is likely to object to this request. The time and expense are tops on the list of reasons. If you insist on GIA paper to accompany your stone, choose a stone that has already got the report. Most jewelers will have a selection of GIA graded stones that you can choose from.