The 34-35 Centenary florin that recently sold for $651 is obviously fake to an experienced eye.

There are guides to help discern the differences between known fakes and genuine coins and they are excellent, but those of us that have been collecting coins for several decades know what the real thing looks like - and from what I see on eBay today - some are rubbish and some are genuine. It takes a few seconds to spot a fake and it's the obverse that tells the story.

The scammers buy the slabs here:

https://www.aliexpress.com/item/1-PCS-Lot-New-High-Quality-PCCB-PROFESSIONAL-COIN-DISPLAY-SLAB-Coin-...

They buy the fake coin here:

https://www.aliexpress.com/item/1934-35-Australian-Centenary-Florin-George-V-UNC/755339616.html

..and the rest is history.

I see 'Gold Krugerrands' selling for about $1800 which are gold plated tungsten garbage.

I also see a skilfully crafted 1d 1930 penny forgery which is acording to the seller 'genuine' and is actually 'not geniune'.

eBay's policy is caveat emptor.