I'm a fan of drawn seals/sigils/talismans (men?)/etc incorporating symbols.
I noticed, however, that while many of the materials that had been used by alchemists (antimony, copper, lead, silver, gold, etc) had symbols to represent them, most of the "birthstones" did not.
I wanted to be able to incorporate birthstones into my drawn works, so undertook to create symbols for them.
Before doing that, however, I had to figure out which stone went with which month, and which stone went with which zodiac sign.
The process for that was to find as many different historical sources for birthstone < - > month / sign associations as possible, and tally up how many times each stone mentioned, was associated with each object. At the end of it, the most commonly-referenced stones for a given sign or month, were the ones that I used.
The Curious Lore of Precious Stones (George Frederick Kunz) was my main (though not only) source for this.
Then, drawing on my own knowledge of symbology, I tried to come up with symbols that were in some way representative of the stones' purported powers and zodiacal, elemental, and planetary associations. This was a several-day undertaking, collecting and sorting through the deluge of magical powers and correspondences ascribed to gemstones, and I don't think I'm done yet. In the end, I came up with this:
(Inserted Image)
Hopefully, this will help anyone looking to symbolically represent birthstones in graphical magick work... and the more people who ascribe significance to these (or any) symbols, the more powerful they'll be for everyone, right? ;)