I actually have two gems, which are equally awesome:
- The Biddle Trick
- And 2-card monte
They aren't well known tricks, and aren't performed often due to the uncharacteristically high volume of knuckle-busting sleights involved in the tricks. That's what makes them my gems.
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On a serious note: I will list only the abbreviations for my tricks, and a short description on most. Doing that so that none my names are stolen

. I will also be sure to only list card tricks, as that is all I'm sure this thread was created for.
WTF: No description for this one. This is an absolute secret for magicians. Aptly named because that has been the first few words out of almost every crowd I've performed for, and those who choose not to say words like that have a look on their faces

. But I do need a new name for it.
TGP: A impromptu transposition in which the spectator sees both the cards before they are placed in/on separate locations. Very openly done, both cards are away from the performer and turned over by the spectator.
F: Card selected, lost, and after some magical mojo, the three companion cards are revealed. Combines some nifty transposition effects with a nice ending phase.
P: Card selected, placed into deck, shuffled by spectator, spread on ground, knife introduced, moved around over the randomly spread cards, spectator calls stop and performer stops moving the knife, stabs card below. shown to be selected card.
R: A 'variation' on a TNR. More of a complete modification, but it was inspired by a certain TNR.
C: A couples' trick.
I have quite a few more, but I'm bored of typing and see no real point in this anyways.