Formula 1 b3 b5, so in the key of C that would be C Eb Gb 864xxx. Handy to learn for when your not sure whether you should be playing a dim7 chord or a m7b5 chord - this chord covers both by missing out the 7th!
Here are dim chords in open postion for the CAGED shapes:
Cdim: x31x12 (can use thumb on the 5th string if you can't stretch up with your little finger) [EDITED thanks to Phil_aka_Pip's post below]
Adim: x01215 (top string optional - IMO sounds better without)
Gdim: 31x023
Edim: 0120x3 (could play open top string but then you've got nothing with which to dampen the B string)
Ddim: xx0131
Comments
x31212 (x C Eb Bbb C Gb = x R b3 bb7 R b5)
Plus, the nice thing about diminished chords especially if you resist the temptation to double the note you think of as the root, is that any note can be the root as these chords are often inversions of each other. The top 4 strings of the Cdim chord could also be Ebdim, Adim, F#dim.
Seriously: If you value it, take/fetch it yourself
Seriously: If you value it, take/fetch it yourself