The Rare Japanese Tama 6yo Stamp?

I was advised that many of the pre-1900 issues are forgeries. Some of the forgers even leave their signatures on the stamps. Just looking at ebay, there are many early issues for sale at a bargain. I think anyone collecting early Japan needs to be careful.

Exactly. I'm no expert, but I have studied under someone who is. The thinking is that for the early Japanese stamps, the forgeries outnumber the genuine by a factor of at least 10:1, and on some issues perhaps as much as 100:1.

But this is also a problem for other countries as well (although Japan's situation is unusual because there were local forgers creating items to sell to the tourist trade). So, for this worldwide collection you are considering buying, my advice would be to not assume you can identify a high catalog value stamp that the dealer/seller has overlooked. They are very likely forgeries.

Philatarium, for the worldwide collection, there are probably some gems in there, but many forgeries as well. I will probably give it a miss as I don't actually collect most of those countries.