I traded for the engraved SAA over 20 years ago and I had no idea how rare it was until I was reading the new book on Colt SAA's that (Don and Carol) Wilkerson and Kathleen Hoyt wrote and published a couple years ago. When I read the paragraph about "the first engraved revolver listed in the records" going to Benjamin Kittredge on July 30, 1877, I thought "that serial number sounds close to mine." When I checked the serial number on my SAA, I was stunned.
The information on this gun was most likely 'dug out of the records at Colt' for the book by the then Historian, Kathleen Hoyt. I found it odd that the original letter from Colt did not list this fact, but I guess such information took more 'digging' than was done when the original letter was requested over 20 years ago.