Galadriel,
Why not just ask us? Ok, ok it took quite a number of tries to perfect the technique, so WizardSteve isn't going to disclose it that easily. However, just a word of warning--if you're going to use a soldering iron, remember that overheating your amethyst will turn it brown. And if you are going to try solder (and I'm not saying that's the secret), do make sure it doesn't have any lead in it!
Also--we really appreciate that you did not hot-link to our wand photo--we have a real problem with that, since it uses up our website bandwidth. But don't ever be afraid to ask us for permission to use our copy-written photos. We usually do give permission, as long as it's not being used against us by a competitor.
And if you need tumbled stones or cabochons for your creations, just contact us at Mandarava.com. We have thousands of pounds of raw cutting material, tumbled stones, cabochons, etc., mostly "old stock" from my retired parents lapidary supply store.
Thanks.
Padme at Mandarava.com