Yes, moissanite stones pass diamond testers. Diamond testers work by measuring a stone’s thermal conductivity. Moissanite and diamond have an extremely similar thermal conductivity, which is why moissanite tests real.   We should note, there are some commercial-grade diamond testers (extremely rare) that claim to be able to differentiate moissanite and diamonds. But these aren’t always reliable and actually fail quite often at differentiating the two.