If I lie on the MediCrystal Mat on my stomach, can the FIR heat damage implants or genitals?

Please consult your health professional regarding this. There are studies on PubMed about heating genitals actually to induce reversible male contraception. In general, it depends on the temperature you choose. If you aim to maintain fertility, make it warm instead of hot, and it should not cause any problems. 

So — if contraception is not your aim, If you lay on the mat on your belly, it is important to protect your genitals. Usually, two mats are used, one under your leg zone and the other under your stomach, and you leave a small space between them for the genitalia not to be affected.

Another possibility is to make a non-permeable for the FIR rays screen. It can be done with a towel folded many times and covered with several layers of standard aluminum foil. It helps for short procedures.

As for silicone implants, they can get warm because of FIR rays. Silicon is usually heat-stable, but it’s better to consult your surgeon if you lay on your belly in high heat mode.