A c. 1760-70 late Rococo Portuguese bracelet clasp, set with golden imperial topaz and minas novas quartz in an openwork silver frame of mirrored floral scrolls, fitted with a modern beaded strap of imperial topaz, white topaz, quartz, and freshwater pearls. In total, the 16 faceted and 36 beaded imperial topazes weigh approx. 72.84 ctw. Two bracelet clasps from the same period are in the National Museum of Ancient Art, Lisbon (inv. 293J & 825J); both feature golden topaz and clear quartz in openwork silver frames. In particular, inv. 293J is of the same dimension as the present clasp (39 mm height) and also has 12 eyelets along the edges. The dense spacing of said eyelets suggests these clasps were originally sewn with ribbon straps, or fitted with strands of seed pearls.
The quartz foiling has been painted with a prominent black dot to imitate the deep, well-like cutlets of old mine cut diamonds, a practice common for paste jewelry made elsewhere in Europe. Pastel colors and flirty exuberance being core Rococo aesthetic tenets, European jewelers of the 18th century often had to rely on faceted flint glass (paste) to take on the appearance of large color gems, in cases where mined gems were prohibitive in expense, color, or available size. However, paste jewelry never caught on in Portugal; the same Rococo designs that might have featured paste elsewhere in Europe were almost always made with genuine color gems in Portugal, the reason being that the Minas Gerais region of Brazil (then a Portuguese colony) yielded plentiful topazes, beryls, chrysoberyls, and quartzes. Offering both color variety and size, Brazilian gems were heavily relied upon by Portuguese jewelers and are featured ubiquitously in Portuguese jewels. In particular, topaz from Ouro Preto is dubbed “imperial” if in a desirable color variety, and became a widely beloved gem by c.1750, following the discovery of deposits in Vermelhão, Rodrigo Silva, Dom Bosco, and Capão do Lana within the Ouro Preto region during the 1730s. For example, a 1759 inventory from the Duke of Aveiro references topazes most frequently, more than all other gemstones.