These tongs are patterned.  They are Queen's pattern with a lovely twirling pattern on the back of the bowls. There were many different patterns produced from the early Nineteenth century onwards. It can be very difficult to identify the precise pattern and different companies sometimes used slight variations. The best reference book to identify the patterns is Ian Pickford's "Silver Flatware, English, Irish and Scottish 1660 - 1980". These tongs are dated 1830/31.

The earliest tongs I have seen with a pattern (a simple shell) are dated 1797 by Eley & Fearn but by 1830, the date of these tongs, the patterns appear on very many tongs, as they did with most flatware.