It is not a complete analysis so I'd suggest searching for "nutritional analysis cuttlebone" or something along those lines. The above website was the best I could come up with on short notice.
Cutle bones are often given to Sulcata torts for added calcium instead of calcium powder. I can't imagine it would be "wrong" to use them for geckos too. Just make sure you use a screw driver to pop the Calcium part of the cutle bone out from the backing.
For torts, this is easier than powder, because they will chew on the cutle bone at will, and dusting straw/grasses doesn't work so well. The trouble involved in grinding it up into a powder vs how cheap calcium powder is....Just buy the powder. It hardly seems like the few bucks you save is worth all the extra trouble.