Ok, this is where I give away my darkest secret. I don't use pickle to clean firestain off silver! Shock! I use cream of tartar, I expect loads of people know that you can use this to clean metals, silver certainly, copper just goes green! I mix the powder with either water, or water and lemon juice if I'm in a hurry. Just until it's a thick paste, too runny and it won't coat the piece properly. If it get's runny add more powder. It comes in a tub for about 30 or 40 pence in a supermarket baking section.
You now need to mark the silver for drilling. You need to measure the holes drilled in the stone so that the holes in the silver match up. You can mark with a fine steel point through the pebble's holes, or if you are very clever or have a suspension unit for your drill, you can drill through the pebble into the silver, I don't recommend it though as the silver can easily slip out from under the pebble and you can end up with a hole where you don't want one. I use a good pair of dividers and a rawhide mallet. Measure the distance between the centres of the two holes as accurately as possible with the dividers, then place the points on the silver in the right place and tap with the rawhide mallet to mark the silver slightly. Make sure you are not too near the end and in the centre of the strip, also remember, you need enough space above the pebble for a chain or leather thong to thread through once the bail is bent in half! In other words don't put the holes too far from the end of the silver strip. Once you have the marks at one end mark the other end, trying to keep the same distance from this end of the bail. Hopfully you have measured your wire properly before you started, to fit on the pebble comfortably with a sensible loop above it when you are finished.
At this point either clean the prepared rivet as before, or leave it as it is if you like the oxidised look. The next step is to form it into an actual rivet. To do this properly you need a drawplate, a flat bar of steel with a variety of holes through it. They can be expensive but I got mine from an engineering firm and it was very cheap, I searched the internet for it. Put the prepared wire through the appropriate hole in the plate and hammer the end flat,
|melted wire in the drawplate|
Here's the rivet head,flattened, in the draw plate, top left corner. Make another.
All that's left is fitting it all together. You'll probably find that the holes need to be juggled a bit until the first rivet is in place. Place the pebble on a flat metal surface with the unfinished end of the rivet uppermost. If necessary trim it until only a short piece sticks out beyond the silver bail. Now carefully hammer this end flat. This is tricky, you need to ensure that the already flattened end of the rivet is firmly against the surface, with a natural pebble this is not easy, but if this isn't happening the rivet will just fall back through when you hammer it. You're aiming for a flat end rather than a bent over one, although as long as the rivet is firmly flat against the bail surface and you like the way it looks then that's ok. Once both rivets are fitted and properly flattened, file any rough or sharp edges smooth and there you are. Thread the pendant onto a chain or a length of thonging to complete it.
Here's one I made earlier.