There have been numerous counterfeiters caught lately; the chips they are trying to pass are doctored low denom chips, made to look like $100s and $500s (I think there have been $25 chips done, as well).

Now, look at the risk to the thief; would you rather have your bogus chips scrutinized by a cage cashier, or by some buyer on Ebay that you don't even see? I'm actually not surprised to see hints of widespread chip-fixing, since the markup can easily go to over $500 per chip... Now that I hear collectors are knowingly paying for chips to be repaired - it also doesn't surprise me that these doctored chips will eventually migrate into the public domain (collectors die, chips get traded & re-traded).

In the end, a drill hole (sort-of)proves authenticity. I've run into the exact same situation in collectible slot machines - when they become worth $2000+, you have people trying to pass modern castings off as original machines. FYI, doing new castings was an affordable way to replace key metal pieces that had cracked - but raised the possibility of somebody constructing an entire machine out of the castings... SO, the problem comes down to this: some collectors like dirty, used pieces (drilled) - while some want mint, perfect (now, increasingly/possibly fake). The sad part, is I think this makes a perfect opportunity for slabbers to justify their fees on rare chips...