Hey Robert!

Great idea! I've seen four different types of security dots so far...

Granted I haven't looked for them as much as I have differences in UV markings. They are usually on chips with denominations of $25 and up! And unlike Greg, I don't collect $100 and beyond chips... <VBG>
It also takes more time to pop them under the Microscope than it does to just pass a hand held UV light over a group of chips... Page 44 of Chipology 101 shows one of the four....

Regards,

Dick