This is a Golden Nugget $20 baccarat chip, used not too long ago in Las Vegas. I got it on eBay about six years with only a casual mention of the insert error. It has Vee-shaped inserts and half of one of the split Vee's is missing! One on the left is the normal chip. Edge view shows that the entire black insert half is missing. It's hard to visualize how this error was made unless they put extra black and orange clay into the notch and it squished out to fill the gap.