Here's a thread:
http://www.tarotforum.net/showthread.php?t=268224&highlight=Crystals
Recommendations - try asking in the Crystals and Herbs section of AT?
And 3 that come to mind:
Clear Quartz - is an amplifier. And "promotes and intensifies spiritual expansion, awareness and enlightenment".
Dark purple Amethyst (Brazillian or Mexican) - promotes spiritual awakening and links to guides, angels, Goddess and other realms.
Celestite (watery pale blue) - as above, plus access to ascended beings, and advancement of channelling. Manifests ability to "flow with life".
- I looked the full info up in Diane Stein, "Healing with Gemstones and Crystals".
(I've not seen Celestite in a tumblestone form... usually it's faceted points... so it would be "scratchy" to
keep bouncing about inside a bag with a deck of cards. Quartz and Amethyst, you can easily find in tumblestone form.)
Some of my decks have a resident crystal inside the storage bag.
I choose them by "feel" - so I'm not thinking of the "designated metaphysical properties",
but rather just matching them because they somehow make sense with a particular deck for me - if you see what I mean...
Here are two with their decks (sorry photo's are fuzzy)
1) A red (orangish with stripes - feels a bit "comical") Jasper heart for my Halloween Tarot.
2) A Tiger eye heart for my Pagan Cats Tarot (you get the "cats eye" ref here

).
3) Faceted Clear Quartz - I like to place the large one by my card spread
when reading for others - and think of it as an amplifier for all needed and useful information. The faceting creates a Merkaba (star tetrahedron of sacred geometry) and Hexagram visual... "as above so below" and all that jazz.
