Choosing a crystal ball

Although its popularity may have peaked in the early 20th century, the crystal ball is still the most quintessential of all scrying devices.  Some modern practitioners, especially professional psychics, shy away from them because of their gypsy/carnival reputation.  But many people cherish crystal balls for their romance, beauty, and unique properties.  If you're in the market for an orb of your own, here's a few things to consider:

Understand the different products that are available. Solid quartz crystals are cut from a single piece of natural stone, and almost always contain what jewelers call "inclusions," or flaws.  Most are less than two inches in diameter, and larger specimens are rare.  Fused or reconstituted quartz balls are made from quartz and sometimes other minerals that have been pulverized and reformed into a spherical shape.  These come in many sizes, and generally have greater clarity and a lower price tag than solid cut quartz.  Glass spheres contain no quartz, but are made of silica dioxide, and may be perfectly clear or display small air bubbles inside.  These are the cheapest scrying balls available, but they may lack the metaphysical properties attributed to genuine crystal.

Also, while clear quartz is the most traditional material, it's not the only option.  Smoky quartz, rutilated quartz, and colored stones like amethyst all have their fans.  Crystal pyramids, tetrahedrons, skulls, and natural shapes are all popular alternatives to spheres.

Spend only as much as you (comfortably) can.  Real quartz can be extravagantly expensive. Frater Achad makes a good point when he writes,

We should choose this crystal, I might almost say, lovingly; at least, if a selection is presented to us we should take the one to which, after a moment of silent consideration, we feel most attracted; and this -- if possible -- regardless of the material consideration of its cost. We should not, however, purchase a globe which is far beyond our material means, so that other obligations would suffer thereby; otherwise, lurking at the back of our consciousness whenever we use it, may be the feeling of having acted wrongly in that connection from the very start.  (Crystal Vision Through Crystal Gazing, 1923)

Realize that the true power of sight resides in the seer--buying the biggest and best tool you can find won't help you if you aren't willing to put in the work of learning to use it.  You can get very good results with a small crystal.  And remember that you aren't wedded to one crystal for life.  You can always upgrade later if your interest intensifies or your financial situation changes.

It's better to try before you buy.  If you're lucky enough to have a crystal supplier in your area, go there first.  The staff will usually be happy to let you grope all the crystals and answer any questions you might have.  In a store, you can hold a ball up to the light to check the clarity.  You can look at it from all angles and examine its inclusions.  (Some people find that the swirls, clouds, and streaks in natural crystal help to trigger visions, while others find them to be distracting.)

Try clearing your mind and see if there's any stone you feel particularly drawn to.  Do any seem to be humming, singing, or calling out to you?  Pick 'em up.  A tingling or warm feeling in your hands, forehead or gut is a good sign.  If you start to see images immediately, then that's even better.  If you can't get to any occult or crystal shops, some alternative sources include gemstone conventions, antique stores, Celtic festivals and Rennaisance faires.  (My first crystal ball came from a rural Rennaisance faire--in the South, these places are hotbeds of sublimated occultism.)  And it goes without saying that you can order one online, but caveat emptor--it's really hard to judge the quality and size of crystals from pictures.  Also, many rock crystals (especially the ones on eBay) are imported from Asia and the high shipping costs negate any savings.

Treat your new tool with respect.  No, you don't have to buy into every dogma and superstition ever created about crystals. Yours will work just fine, even if you don't bathe it in herb tea and swaddle it with silk and consecate it under the light of three consecutive full moons.  (Although you can do those things if you really want to.)  I think at the very least, though, you should cleanse a new crystal thoroughly, and perform a simple ritual dedicating it to its best and highest use.  You should also store it someplace safe where it won't be disturbed until you're ready to use it.  Personally, I've come to think of my favorite crystal as a trusted collaborator, and to regard it with a kind of grateful awe.  It's been in the Earth's crust for millions of years, after all, and now it's come along to help me do my work.  Whether or not the crystal actually possesses any properties of consciousness is beside the point--adopting an attitude of humility and patience will prove most helpful in any metaphysical pursuit.