here's one I think is absolutely beautiful.
http://www.cakecentral.com/modules.php?name=coppermine&file=displayimage&meta=search&search=tiara,%20crown&cat=0&pos=1&search=tiara,%20crown
i've seen people talk about candies that look like jewels, i've no idea where to get them. maybe make the cake whhite and paint accents gold, maybe a jewelry box, with the jewels in them?
I was in hobby lobby the other day and next to the candy melts and molds they had some hard candy molds and the mix to make them i bet you could make hard candies i nteh shape of gems and use the gem tones on the cake maybe ice it white and have gold accentsmaybe use fondant to make gold pearls for the borders and maybe make a string of gold pearls to drap off the side of the cake. Not sure if this is a stacked cake or a sheet cake
There is a cake posted by hockeymom that looks like it has drop jewels on it. I believe she made them from royal icing and then used lustre dust on them. You could do that, make jewel toned royal, pipe them and let dry then use jewel toned lustre dusts. You could make the diamonds, well, diamond shaped, the rubies oval even emeralds in an emerald cut shape.
Next option might be to just break up some coloured hard candy and put them in gold painted fondant settings.
Sounds like this is going to be a pretty cake!
i have a customer who's daughter is turning 16. she wants a cake with the colors white, gold, and different jewels, like rubies and diamonds. i have no clue what to do or what to use.
any help would be much appreciated! 
OMG OMG Diane!!!!!!!!!!!!!! I am so glad to see you back!!!!!!!!!!!!!!!!!!
If you decide to use hard candy molds for the jewels, here is one: http://www.confectioneryhouse.com/?Screen=PROD&Product_Code=HCA0691055
Quote by @%username% on %date%
%body%