Sourcing Rough Opal
One of the biggest problems facing an opal enthusiast can be where to find rough opal. After many years of networking, most hobbyists have their contacts built up among dealers and cutters. But what about those of us first starting out? Or when we're stuck in an area without any local contacts? How do we find opal then? In this article are listed a few simple ways to find opal without actually digging it up ourselves. ;-)
Gem Shows
Nearby gem shows that opal dealers go to are a wonderful source, as you can actually look over the material they have and see the quality for yourself. Most dealers are also very nice about letting you pick through groups of stones and buy individual pieces. Of course, picking out the individual stones like that will generally cost more than the parcel method, but sometimes it is well worth it to get exactly the stone you want. Most opal dealers will have a list of what conventions they plan to be at every year. If there is a particular dealer you are interested in buying from, you can also "suggest" a convention in your area and if there is enough interest (i.e. possibility of making enough money to cover the transportation costs) then they might come out to your area. 
Bob's Rock Shop keeps an excellent listing of convention dates and places.
Going to the American Opal Society's yearly convention in Los Angeles gives an excellent source of multiple opal dealers all in the same place, not to mention all the wonderful exhibits and symposiums that are usually presented. For a future long-term relationship with rough opal, the most important thing to do is to get the names and cards of the dealers there and finding out where they are going to be in the next year. The AOS convention is usually held the first week in November.
As always, another wonderful place to be every year is Tucson, Arizona for Quartzite and the Tucson Gem and Mineral Show held every February for several weeks. Hundreds of dealers from all over the world go to this, and a lot have come straight from the mines and cutters with "never seen before" opals. Tucson can be the *prime* spot for the best rough opal. Be prepared to spend a lot of time, and a lot of money!
Opal by Mail
There are several opal dealers who sell parcels of rough opal through the mail. For stay-at-homes like me, this can be an excellent resource. One way to find mail-based opal dealers is to buy a copy of Rock & Gem, then ask for a price and source listing from every dealer mentioned in the ads. This will take a day of work and about 30 or so letters, but the resources you get back are usually worth it as you then have several comparable sources. A first time buy from any mail order place should be done within a strict limited money range, and very carefully mark down on your list what the quality was of the stones that you ordered. For example, almost everybody has different levels of 'quality' from potch on up. Pick a mid-range comparable quality and price on the lists, buy equal amounts from the most likely sources, and then see who has the better product, and mark it on your list. Most serious mail order opal dealers will also offer to send samples and are eager to communicate with the buyer as to your individual needs.
Opal by Web
The newest and most "with-it" resource for finding sources. The web can be a mixed bundle when trying to evaluate what type of rough opal to buy. There are many dealers who now have websites, and some of them will even put pictures of their rough parcel material up on the site for viewing. However, we all know just how hard it can be to take a good picture of an opal – let alone the rough material! One of the advantages of the web is that a good dealer will update their site often with lists of parcels and prices, and some of them will send out emails when they get new shipments in. For a long-term relationship, this is a very good way of knowing the source. When first buying from web-based dealers, as a general rule, treat them in the same manner as the mail-based dealers. Bookmark the sites, compare basic quality and prices, and then buy small quantities of the same range. When the opal arrives, mark down on your sheet how the sources compared. To find web-based dealers, do a search for "rough opal" on any of the web search-engines, or check out the links on the AOS website or Bob's Rock Shop.