Hi Celtic,
First of all, a beautiful dress and gorgeous colour!
I think either clear, or aurora borealis crystals - if you went for a colour, as others have said, a deep blue would go nicely. Do you have another colour in your theme that you could use? Is your dress white/ivory? If so you could always have pearl (ie white/ivory) and blue necklaces to bring in both the colours of your dress and your bridesmaids - I had a bride who did this last year. She had turquoise bridesmaids and wore ivory, so we put the two together in the necklaces for both her and the bridesmaids (and also in the other jewellery and tiara/headbands), and we also brought the pearls and turquoise crystals into the bouquets for a complete 'look' please see http://www.orchardtwist.co.uk/gallery/g-artemis.shtml for the collection I did for her.
Hope this helps.
Sharon.