The identification of Caithness "Pebbles" is a nuisance - they come in several styles, quite a few colours and colour combinations, and (officially) two sizes; their irregular shape makes it difficult to define dimensions - and likely sizes varied in production a fair bit as well; the fact that the Charlton information is partly wrong (style two, page 72, issued 1986, lists the colours of the 1994 editions) doesn't help.
- Style one (1984): catalogue shows 3 colours (production codes, though more images), no size given, but only 1 size shown; Charlton mentions "many colour variations", no size given.
- Style two (1986/87): catalogue shows 4 colours 1986, plus another one 1987, no size given, but only 1 size shown; Charlton lists 6 colour combinations (actually issued 1994) and 2 sizes (medium & miniature).
- Style three (1994): catalogue shows 6 colour combinations in 2 sizes (example attached); not mentioned in Charlton in 1994.
Andy Nowson (Encyclopaedia of Caithness Glass Paperweights
) gives ranges for 2 sizes:
- Mini: 46 ... 56 mm
- Medium: 65 ... 82 mm (which would be rather large for spherical "medium" weights!).
To confuse things a bit more: the miniature weight (style three) is called "Pebble", the medium size is called "Large Pebble" ... in the catalogue ... have never seen one "in the flesh" where I am sure about identification.
Now - the number on your weight will be C57288 - the C indicating 1985 or 2005 as year of manufacture. The 2005 catalogue, however, lists only miniature pebbles, specified "Width/Ht. 56mm/2in" (whilst I think 2" = 51 mm). So your weight must be a style one, first issued 1984 - and the single size then will have been rather large.
I assume, by now you are as confused as I am