What's the difference between opium and laudanum?

It's interesting to me that not the moonstone, but rather a different exotic import (from India), would be the thing with strange and mysterious powers.

Greatness beyond comprehension. The sublime was a concept heavily discussed in English art and philosophy in the century preceding the writing of The Moonstone. Much like the intoxication of opium, the mystery of the Moonstone cannot be explained through calculations or logical argumentation. It's not Law - I think Mr.Bruff's presence in the scene serves as a great foil here. The mystery can only be solved through experience, not deduction.

Such an interesting way to describe the effects of opium. 'Spiritualise' means "to purify from the corrupting influences of the world." However, its definition juxtaposes the 'corrupting' nature that opium has to an individual.

This seems to suggest that Franklin stole the diamond under the influence of opium, which is also why he forgot that he ever stole it. This also reminds me of that scene with the three indians and the little boy during the First Period, although I am not sure if the two are connected. It also finally explains the role of opium in the plot. I am not sure how this drug works, but to my knowledge this is supposed to be a pain killer. Not sure how it would make someone 'do things' without recollection, which is the only thing that confuses me about all this. Nevertheless, it would be interesting to see what else happened during the period that Franklin cannot recall, as I am sure that it will be revealed at some point later on.

How close were Wilkie Collins and Lewis Carroll? If I'm not mistaken, Carroll originally used this phrase in Through the Looking Glass which was published around the same time as The Moonstone.

As Humpty Dumpty says, the portmanteau could be interpreted as "two meanings packed up into one word" . With Godfrey giving Cuff the keys to the portmanteau, it may allude to clues hidden in words with double meanings.

Either way, Carroll and Collins must've been on a lot of the good stuff.

It should be mentioned that Wilkie Collins was a "notorious opium-eater" himself. The Colonel may be an allusion to himself, and the negative way in which he is depicted could be interpreted as Collins' self-loathing.

The curse of the Diamond itself may be an allegory for the corrupting influence of opium addiction. The "wretched crystal" that he "picked up" in India can be construed as a metaphor for a bad drug habit.

This brings an important issue about our relationship with narcotic substances, dating back from Victorian times. It would be interesting to learn how this plays a role in the story (or if it does) and perhaps it would lead us to uncovering the darkest motives of the character/s.