Thanks to the BASIC source code and plain-text level data, I am now quite sure there is no Treasure 10 and no Rooms 36 and 37.
I love that "icetique" has spent time examining this game's BASIC code. It's worth remembering that Curse of Ra started out on the TRS-80. I wonder if any version of the this game has the two missing rooms and treasure 10?
I just examined the Atari ATX disk version of The Temple of Apshai Trilogy in a hex editor and searched for the word "ruby." Treasure 10 is certainly in the game's code (as data, I guess). Treasure 10, along with the other treasures from level 4 of Curse of Ra are all listed together. In this list, the crystal is called a "LARGE RUBY," which is what the treasure's description calls the crystal. Is this term in the BASIC code of the game. Is that information useful?