The chance of searching into the loss of the Moonstone, is the one chance of inquiry that Rachel herself has left me.”
Throughout his narrative Blake repeatedly links the mention of Rachel to the mention of the Moonstone / Diamond. I would be interested in running a word colocation / frequency analysis to see how often this happens in Blake's narrative and throughout the rest of the text. It may also be worth while to do a sentiment analysis and see what the tone is for each mention based on which narrative it came occurred in.