A guilloché sterling silver cap with the hallmark Ag 925, combined with a black precious resin barrel, identifies a Meisterstück Solitaire Doué. Doué means that the cap alone is made of precious metal, while the barrel corresponds to the classic Meisterstück. The pattern of fine, closely spaced lines is known as a thread guilloché. Together with the 18 carat nib, which bears the number 4810 and thus the height of Mont Blanc in metres, this gives the Meisterstück Solitaire Doué Silver 146, that is to say the middle size, Le Grand.
The other markings on the cap are not model indications: the combination of letters and figures is the serial number, and the remaining stampings concern the quality of the metal and the country of origin, Germany, and form part of the usual hallmarking. Cap material, pattern, nib size and overall size are therefore enough to identify it. The 146 is a piston filler, drawing ink straight from the bottle, and sits in size between the slimmer 145 and the large 149. That a boutique could not readily help is nothing unusual with older Solitaire variants.