Harlequin opal example
The white milky opals break or crack easier than the 'black' opals. There are so many types of opals that durability depends on which type you have. There are white, black, boulder, triplet (a thin layer of opal over some other material, not considered a real, solid opal), from Austrailia (Lightning Ridge or Cooper Pedy), from Mexico (either orange cut opals or clear jelly opals). Then there's lab created - usually set in .925 silver. Also there are what's called "opal inlay", which is absolutely beautiful in black opal set in white or yellow gold (Kabana makes the best of these).
I have a collection including all of the above mentioned. Don't get a boring white opal with no color. The more color and fire the better the stone.
Examples of opals
http://www.aussietreasurechest.com.au/shopdisplayproducts.asp?id=3&cat=Solid+Opals+$500+-+$1000
I can't recommend this site, it's just an example to give you some pictures and idea of stone quality and price.

The white milky opals break or crack easier than the 'black' opals. There are so many types of opals that durability depends on which type you have. There are white, black, boulder, triplet (a thin layer of opal over some other material, not considered a real, solid opal), from Austrailia (Lightning Ridge or Cooper Pedy), from Mexico (either orange cut opals or clear jelly opals). Then there's lab created - usually set in .925 silver. Also there are what's called "opal inlay", which is absolutely beautiful in black opal set in white or yellow gold (Kabana makes the best of these).
I have a collection including all of the above mentioned. Don't get a boring white opal with no color. The more color and fire the better the stone.
Examples of opals
http://www.aussietreasurechest.com.au/shopdisplayproducts.asp?id=3&cat=Solid+Opals+$500+-+$1000
I can't recommend this site, it's just an example to give you some pictures and idea of stone quality and price.