Let me tell you my personal thought process, with usual disclaimer: your mileage may vary

1. First and foremost its GOLD! If its made from GOLD, unlike any other bead that made out of wood/clay/glass/agate/rock/paper/etc... it has very easy calculated value that always above 0!!! Its purity x price x weight. If you buy fake/new GOLD pyu bead same day 10yrs ago, just based on material price it went from 340 per oz to 1680 per oz, i.e. 5times in 10yrs! If you buy any other bead 10yrs ago, and its not antique, old, real - price of it 0 and will stay 0

2. Any person who buy anything that selling as gold, must test if its gold! Home gold testers are not very expensive and they will tell you gold contents in object you are buying. In case of Pyu beads its always 70-80%, so you can calculate material value very easy using above formula (see 1)

3. In case of the picture above, gold is NOT chemicaly treated (unlike pictures posted by moscitobay and will) so it makes easy to see proper patina. As Gold you are buying is NOT 99.9, it ill have proper patina and oxidation unless been cleaned in aqua regia or other acid. In case of Will beads its very evident its been cleaned in acid, so while it can be real - its makes hard to tell.

4. Your beads are very well known type - sphere inside sphere and unlike beads presented by previous pictures, very hard and expensive to make i.e. labor cost is high for these beads - old or new. You can check with local goldsmith, how much will you need to pay to make bead like this.

So lets sum it up:

So, assuming 10yr holding period, if you pay for it anything below (5 x Material) + Labor there is good chance in 10y time you will come ahead - real or not!

Thats my thinking process, so I hope it helps
Best