The answer, with no sarcasm intended, is "whatever someone will pay you for it". Records of past auction sales of similar items, be that of closed eBay listings or another venue, are to my knowledge the only way to get a ballpark idea of the value on something like this. Edit: especially since it is technically a token and not a coin. The price of 0.21 g of gold would be your minimum.
Looks like one in MS63 sold back in 2018 for... $192. MS66 is a good hop up from 63, but I don't know if these are widely enough collected for it to make a big difference in price.
Ask yourself what did these costs me and when? Take a look at the .21 g and today's spot price, then go from there.
I'd think an MS66 grade (and, of course, authentication) would put a California fractional gold piece way ahead of spot.
I didn't say sell at spot. I'm asking the OP what they need to consider to come to a reasonable price point. In other words, take the .21 g and multiply it by the spot price. That will give them a value for the gold alone. Then consider what they paid for the piece as I have no idea. Of course they need to consider the grade and how many were made and a lot of other things that we do not have any information on.
What is that thing exactly? I know gold tokens were made locally in the early days of the California gold rush, but I can’t tell from the slab label whether this is one of those, or something that might have been made later - “1853 DATED” seems to imply skepticism about the date.
