sure - there are two difficulties in the search - as we know, none of the factory drawings provide dimensions plus, so far I can't match the bands of horizontal lines showing on this piece, which is possibly a sugar. Have to say I chickened out of looking through all 125 pages of the Board's pressed gallery for Sowerby patterns.
Small bowls such as this were commonplace shapes, but for reasons possibly lost in the mists of time it appears that they don't start to appear with these opposing projecting handles until Sowerby start their Registrations, and in the 1870s there are several Registrations from that factory for small bowls with such adornment - almost theirs exclusively - as a design feature it's just possible it had its origin in the then current fashion for the aesthetic art - think of the PIQW bowls with similar handles.
Hopefully someone here will recognize this particular design, alternatively you will need to provide at least one of the four pieces of data from the diamond, and taking a punt my opinion is that this will be from the second period of lozenges - 1868 - 1883.
I've tried Cottle's booklet - Slack and Jenny Thompson, though it's not to say I couldn't have missed seeing this design. Also tried the Thistlewood's CD rom discs, though don't think these cover all of the 1870s output - if I have that wrong do shout.
Hopefully one of the pressed buffs here will have the answer for you - best of luck.