VERY RARE - GEM IDENTIFICATION CARDS - C.S. HURLBUT, JR - HARVARD UNIVERSITY!!!

Description

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I will be listing several items that belonged to my Dad today.  We have been going through his study and trying to find new homes for many of his things. He would have been happy to see them continue on with someone who appreciates them as much as he did.
This listing is for a very rare set of Gem Identification cards.  This truly unique concept was very effective in narrowing down the possibilities of different gems based on Refractive Index, Specific Gravity, Hardness and Color along with several other characteristics that separate one gem from another; i.e., opaque, translucent . . . dichroic, multi-colored, metallic, etc.  Using your equipment, determine the RI, SG, etc. and narrow down the possibilities with these cards.
I have a GREAT STORY that accompanies these cards.  About 45 years ago I was doing a gem show with my Dad in New Hampshire - he was focused on his lapidary work and I set up a Gem ID table for myself (I was 16 years old at the time).  A gentleman came along and handed me a blue gemstone and asked me to identify it, saying that he would return in about a half hour.  Using this very set of cards (which I love!!!), I told the gentleman upon his return that his gem was an Iolite.  He was astounded because no one else had been able to identify it.  He asked what the determining factor was, because so many gems have the same characteristics.  I told him that I found it to be trichroic.  As it turns out, he was a Curator at the Smithsonian Institute in Washington, DC and invited me to visit him next time I visited there - which I did.  It was a great day for me and brings back wonderful memories.  It also goes to show how effective this card system is.
Anyway, these cards are tremendous.  You just stack them all up together, push the pin tool into the hole that is associated with each characteristic, and the unrelated cards fall to the table.  You are eventually left with just one card on the pin - there's your gem Identification!!!  Amazing!!!
We are willing to part with this set of cards, as shown, and hope they bring much happiness and satisfaction to the next owner.  Please see photos for more details and condition.  They are quite old.
Happy to answer any questions.
Thank you for looking!!!