Jenny Ray said:

Agate and other glass like stones (such as obsidian and thunder eggs) will get hotter than the water they are in,... so be careful when removing them from the heating unit, they also take longer to dissipate the heat, so check on your own wrist before applying to a client....

I usually use four pairs of stones during a massage, and I end up using the same stones several times. My heater is set at a temperature that is higher than I can use on my client so it re-heats the stones fairly quickly, but not so hot that I can't reach into the water. I keep a bowl with cool water beside the heater and dunk the stones for four or five seconds to cool them. I also have a towel handy to dry the stones before using.

I bought my first set of stones from a massage supply catalog. The 40 stones cost $99.

I got my second and third sets of stones when I installed a rock garden in my office.

I used 900 lbs. of Mexican River Pebbles in the garden, which are naturally-polished basalt stones. I paid $30 per 70 lb. bag (which is about 5 gallons) from a supplier of landscaping stones. As I was putting the stones in place I pulled out ones that looked like they would work well for massage -- the right size, smooth surface, no cracks, etc. Except for a couple of larger (6 inch) stones that I use on the abdomen or lumbar area, I looked for pairs of stones that were similar in size, shape and thickness.

By the way, the plants in the garden are real.

Good for you!!....This is exactly what the stone companies are doing...they purchase about 12 yards (one dump truck) at a time and this is about 10 tons of stone, then they bulk tumble and hand sort...the shipping, manual labor, import tax (if they had to come from Mexico...Baja generally), or just transportation if from Southern California (in CA stone harvesting is limited to those who have mining claims staked on the stones)...so $30 per 70# is a bargain!!...
These are high quality basalt and will only improve with use. We should all request our local landscapers carry this product so we can always have an abundance for our students!!
When I taught at the Hilton Hotel Spa in Cabo San Lucas a few years back we had an interpretation problem so I arrived to find tiny toe stones ready for class...we harvested from the fountain and the flower beds which worked perfectly!!...
Jenny Ray