Despite being highly polished this cabochon has a slightly faded appearance which is why it attracted our attention. Black inclusions of manganese oxide which are common in rhodonite can be seen on both sides of the stone.
The reason this rhodonite pendant has been reduced is because there's a small firescale mark in the silver. It can just about be seen in our second photo. It's more prominent in the photo because of our zoom lense and studio lighting. When holding it in your hands it's not immediately noticeable.
Firescale resembles a tea stain and can occur whilst the silver is being worked on at very high temperatures. It's caused because of an interaction between the metal and oxygen. It only becomes more visible as the metal tarnishes.
Keeping silver covered with a soft piece of material helps to minimise the build up of tarnish. Tarnish is caused because of an interaction between the metal and pollutants in the atmosphere. The process is similar to what happens to an apple if not eaten quickly after being peeled.