aha! On gems, I can advise. Having had an eldar army for twenty or so years, if there's one thing,
one thing, I know how to paint, its bloody gems.
*MiJ clears throat*hemhemhem
1) Paint it a bright shade of your base colour. e.g. woodland green, scorpion green or the like.
2) shade the top left (or top right, but be consistent for all the gems on the mini) of the gemstone right the way down to black. (you can do this by adding small amounts of black or using deeper shades of green/turquoise/dark blue or even dark brown.) It's critical to eventually go all the way to black, tho.
3) highlight the bottom right (or bottom left, as appropriate) up to brighter shade of your base colour. Yellowish green would be ideal for your gems, even straight yellow at the botommest rightest part.
4) put a teeny weeny weency wee spot of pure white at the top left (or top right), where the black is.
robert's yer muvver's bruvver, you have yourself a gem.
examples include:
http://www.coolminiornot.com/258362
http://www.coolminiornot.com/263528
*edit* ooh, and
http://www.coolminiornot.com/105372
(you can see yellowone doesnt always go all the way to black, and he also sometimes does two lightspots. This is cos he's fecking good. I wouldn't go mucking about with techy stuff like that, but by all means give it a shotty if you fancy.)
and, an example of the same technique done by us mere mortals
http://i84.photobucket.com/albums/k20/m ... arlock.jpg