Ordinarys:
Small, clear glass with colour swirl in centre. (The ones with a red, white and blue swirl were called 'Jubilees', and the all-green or all-yellow swirl were 'cat's eyes'.

Bonkers:
Same as ordinarys, only quite a bit bigger.

Benkers:
Huge, metal ball-bearings, used to smash your opponent's marble to smithereens.

Peadys:
All white, wi th red, blue, yellow and green markings.

Squiglys:
Bonny colours with thin, white lines all over them.

Rainbows:
Silvery-coloured - would shine red, green, blue when held up to the light.

Contributor says he thinks an ordinary was a 'onesy', a bonker or a peady a 'twosy', and a squigly or rainbow a 'threesy'. If you were playing against someone using a benker, your marble was inevitably damaged beyond repair before you had a chance to win. (P.S. he's from Sunderland, so maybe these expressions were local to the area).