Aggie, as you know 22kt gold is 22/24ths gold, and 2/24ths something else. That is by weight, so by number of atoms it's about 90% gold at most.
Making gold chloride involves dissolving it in Aqua Regia (a particularly nasty mixture of nitric and hydrochloric acid). The other components must then be removed until you're left with 99% gold in the solution (pure enough for toning), and the acid removed until you're left with gold chloride only.
I would not like to try it.
Technically speaking, the correct name for "gold chloride" is "tetrachloroaurantic acid" if I remember correctly - or was it "hexachloro--"?
Try searching for the chemical under that name, sometimes it may turn up less expensive alternatives.
Ole is right. Aqua regia is about the only solution that will dissolve gold and platinum. It is composed of equal parts concentrated nitric acid and hydrochloric acid. You will probably find it easier to purchase the gold chloride than the other two nasties.
My experience with this technique is limited, but I remember a lot of fuming, heat release and the obvious requirement to work under a very specialized chemical hood. The reactions can get out of control thermally with the release of clouds of brown nitrous(ic) oxide fumes - not a pretty sight. Once dissolved, the whole mass must be neutralized with lots of caustic soda, ya da, ya da, ya da. Not an easy project and not for amateurs.
Thirdly, in these times of home-made you-know-what, the procurement of concentrated nitric acid will no doubt be an issue as it can easily be use to make you-know-whats. Lets just say that I'm glad my experience is in the far distant past in a galaxy far, far away. That is why my companions changed my nickname from "rocket bob".
That is sweet of Aggie to attempt to become a high end chemist, but not necessary. At one time, about a year ago gold cholride could be found for about 7 dollars a gram. Just thought I would give it a try.
The 13 dollar price is determined by purchasing an ounce of gold cholride; price depends on the market price, which changes from hour to hour (almost). When I talked to the source it was $362 an ounce. An ounce contains 28.35 grams of gold. Sure beats $40 dollars a gram.
Appreciate folks looking into this for me.
As for aqua regia I am well aquainted with that stuff. Very nasty stuff. Thats whey it is kept in glass bottles with glass stoppers to make sure the fumes done eat the caps of other containers. You're right I don't want to mess with it without a good hood. One better than a cardboard one that I can jerry rigg here. Oh well I just trade in the scrap for more sheet.
On the subject of aqua regia there was an article in one of the early issues of Post-Factory Photography a few years ago on how to make gold chloride from gold metal and aqua regia. The article resulted in a rather animated exchange between the editor of the magazine, Judy Seigel, and Dick Sullivan of Bostick and Sullivan. There are apparently some real hazards associated with the use of aqua regia and unless one knows a lot about safe laboratory practice with hazardous materials my recommendation is to stay away from it.