This is a lovely classic piece of antique Victorian agate jewellery.
It is called a "slab agate" brooch - and gets its name from being made on one large solid piece of agate. The agate has nice stripes to the stone - and I have held it up to the light to show this for you. The colour is very like amber - I think this is called a red carnelian agate.
It is set in a simple silver setting with eight little decorative claws on the front - which are attached to a flat oval band on the back - with a nice Victorian pin - and c-scroll clasp.
In fine antique condition - there are a couple of wee nibbles to the very edges of the agate - which are only seen on close up inspection - they are all to the rear of the agate and not on the front. The fact there are very minor condition issues is reflected in my asking price. I think that you can see the losses if you use the magnifying tool on photos showing the back.
Dimensions: 4 cm x 3.5 cm
Fair price for such an attractive piece of antique Scottish jewellery.