Any child of the 80's will remember these little, well, "gems". They're brightly colored little "rocks" that you put in a glass jar, pour the "magic solution" (sodium silacate) over, and wait. In a few hours you'll have a jarful of multicolored, multiheight, slightly lacy and quite graceful stalagmites up to four inches tall. More recent kits include plastic decorations like scuba divers, the little mermaid, castles, and other things you'd expect to find in a fishtank. Rocks can be any color but tend towards the red/orange/purple/yellow shades over blues and greens.

These are great toys and cheap and fun bits of nostalgia as well. But they're not quite as easy as you remember. If you don't follow the instructions CAREFULLY they won't grow right. Also be careful you don't spill the "magic" juice because it stains--after growth is complete, you pour this out and keep the garden under clear water, so there is no more stain risk here. And for heaven's sake, don't try to grow these, or put them in, your fishtank! It's been done before... i actually had a customer at aquarium world this summer ask why her fish died after she put magic rocks in her tank. The rocks, and the sodium solution are quite toxic to fish.