If you’ve ever laid your eyes upon a beautiful piece of jewellery made of a large quantity of tiny Bohemian garnets set in a brownish metal, you’ve seen tombac.

Tombac (also written “tombak” ) is a brass alloy of copper and zinc, consisting mainly of the former (about 80 %). The exact amount of either, as well as the presence and amount of other metals (lead, tin, or arsenic) depends on when, where and for what use the alloy was made.

Tombac has been used for both decorative pieces, medals and jewellery due to it looking a bit like gold (just like other varieties of brass) or bronze, depending on its composition.

Garnet jewellery set with numerous tiny carbuncle stones (pyrope from Bohemia) was quite trendy in Victorian times, and the stones were often set in tombac. Since the metal would be almost invisible, and a brass alloy would make more sense than wasting gold that wasn’t shown off. In addition, the jewellery was affordable compared to, say, rubies or emeralds, so using gold would increase the pricepoint without really affecting the perceived value all that much.

There is certainly garnet jewellery set in gold available, but the metals look very different and can easily be told apart unless the gold is in dire need of a good cleaning. Silver has also been used, and gilt silver that is a bit worn and tarnished can look quite a lot like tombac.

Is there arsenic or lead in my jewellery?

The good news is that arsenic, if added to the alloy at all, was used to make the tombac look more like gold, i.e. lighter and more yellow. If the tombac you have (or are eyeing) looks more like bronze than gold, as will be the case for most garnet encrusted jewellery, you will probably not have to worry about the presence of arsenic.

Read more about heavy metals in jewellery here.

Sources

OED’s entry on tombac: https://www.oed.com/oed2/00254115