Edwardian Diamond Openwork Swirl Ring Size:5.75 lead was added to glass

lead was added to glass to increase its refraction and dispersion (separation of light into its component colours) and minute quantities of "colouring" elements such as chromium (red and green)

while others believe it was based on  the astronomical clock at Exeter Cathedral which had a small hole in the door below the face for the resident cat to hunt mice

the base is green with gold rim

so an anchor is said to be "fouled" if it becomes caught up in rope

Edwardian Diamond Openwork Swirl Ring Size:5.75 lead was added to glassDATE: Edwardian, c. 1910 A cute diamond swirl ring dating from the Edwardian period, circa 1910. It's set with a cluster of old European cut diamonds and the band is crafted in 18 karat yellow gold. With platinum openwork millegrain settings, creating a swirl like pattern, with four square settings in the centre. STONES Old European Cut Diamonds MEASUREMENTS Head: 11. 1mm diameter Rise off finger: 4. 2mm Width of band: 1. 8mm WEIGHT 3. 2g MARKS