hah - beat me to it!
looks very close, good job :)
Ideally - but you're going to incur a rendertime hit like you wouldn't believe - you'd clone your surfaces a few times (2-5), offset each of them just very slightly inward from the original, so that you form actual 'layers'. Then make a copy of the material which is slightly transparent, and apply that to all but the innermost layer. Play with the transparency so that you get a smooth transition to that innermost layer. Rendertimes increase because you end up reflecting back and forth a lot between layers (include/exclude lists help a bit here) - though you can disable/lower the quality of the glossy reflections to regain a bit of speed here - but if this is for a close-up of a pearl in jewelry, it might be worth a shot; especially since you can just save the file and re-use it later.