I have had a strong interest in gemology since perusing the gems table in my 5th edition Tunnels & Trolls rulebook (the game that got me into RPGs originally) and wondering (a) exactly what certain gem types actually are and (b) how their relative value is determined. For others who are curious about these things, I can't recommend this product enough. Even if you're not interested in the details of gemology, and just want more detail in the descriptions of gems that your characters are acquiring, this is still an excellent product, and a great bargain for its price. If you're not willing to be convinced by a review, then download the free sample product and decide for yourself.
I'm eagerly awaiting future volumes in the All the Treasures of the World series to see what other brilliance the people at Faster Monkey Games will reveal to us.
[5 of 5 Stars!]