There's no real proven physical properties to crystals, so it's probably just the placebo effect if you felt a change.
That said, if it helped you psychologically during a tough time, that's not nothing - it's just that the useful part wasn't the crystal itself but more that you were giving yourself some attention.
On Etsy there's everything, some serious sellers and others who totally hype things up, but at least you've got a nice amethyst on your table now, so you didn't waste your money for nothing.
If you're really looking for a boost when things are rough, you're better off with a good bike ride or talking to someone honest.