I wrote this up a while ago, but I figured I'd repost it here since it's more likely to be relevant to peoples' interests.
[caption id="" align="alignright" width="300"] English: Six dice of various colours. 4-sided die, 6-sided die, 8-sided die, 10-sided die, 12-sided die and 20-sided die (Photo credit: Wikipedia)[/caption]
When I was very small, amongst the flotsam in our parents' bedside table, I found a set of gems - well, gem dice. Three vintage gem-style, precision-edged, unpainted dice: a d20, a d12 and a d4. I never did figure out how they got there. Both parents claimed not to know and said I could have them; maybe they had a closet D&D habit when I was an infant.
I've collected dozens of dice since - used to work at a gaming store and got first pick of all the used dice and random singles - but when I'm throwing for divination, I only use that same translucent, precision-edged, unpainted style. They still make them, and I've acquired quite a few sets. I usually pick the color(s) that seem most appropriate, but for really serious questions I will pull those originals out.
Now, this style works for me because I'm a long-time gamer who has lots of associations built into throwing dice. I made this up in my chaos magic period. I doubt it'd work for other people; it's half intuition when I read them anyway. But this is generally what I have in mind when I throw them, and whether you can use them or not, I figure people might find them interesting.
d4 - This is good for yes/no questions. 4 is yes, 2 is no, 3 is maybe and 1 is don't ask.
d6 - For this die I use a variation on the old counting crows rhyme. One for sorrow, two for mirth, three for death (ending), four for birth (beginning), five for silver and for gold, six for a secret that's never been told.
d8 - Rangers roll d8s to add hit points when they level up. The d8 tells you how much you stand to gain in the situation - ie. if it's worth it.
d10 - Two of these are thrown to give you a percentage. How much should I give, how invested is he, what are the odds of this working out. (Also, on the rare occasion I'm throwing for something vampire, werewolf or faerie related, I only throw d10s and they can work like less specific d20s. It's a White Wolf association.)
d12 - My favorite character weapons were generally longswords, and I associate the d12 with rolling for damage. I toss it when I want to know how much someone is hurt, or will be.
d20 - This is the most generalized of the dice. It gives a picture of how well the situation as a whole is going and in particular how successful your actions will be. Like all uses of the d20, one is spectacular failure, twenty is a spectacular success, and everything between is a sliding scale.