In the Victorian era, jewellery wasn’t just for decoration. It was another form of communication, like the language of flowers, fan language, and even the placement of a stamp on envelope could send a secret message. The Victorians had something of a fascination with symbology.
As an evergreen, ivy was one of the only plants to remain green during the cold British Victorian winters. Along with the mistletoe, the holly, and the fir tree, it had a major role to play in decorations for the winter solstice and Christmas. So, originally, its meaning was to do with life and eternity. However, over time, it came to represent everlasting love, deep friendship, fidelity, or wedded bliss. Apart from being an evergreen and its twining growth habit, I suspect much of the romantic symbology was due to some types of ivy having heart-shaped leaves.
Ivy didn’t just decorate jewellery, it was also used on gravestones to convey the same meaning. So Ivy jewellery could function as both a love token or as mourning jewellery. Unlike most mourning jewellery, you could keep wearing it after the mourning period. Unless – of course – it was carved from jet.
Apart from being an evergreen and its twining growth habit, I suspect much of the symbology was due to some types of ivy having heart-shaped leaves. A doubling up of the twining and the heart would have been irresistible. So, if you are writing some romance into a Steampunk narrative, you have this kind of metaphor or analogy to fall back upon. Maybe there is ivy present in the garden where your lovers meet. Maybe one of them gets a love token with ivy decorating it. Everybody sends roses … your couple can stand out in a crowd by having ivy as their signature flower.