Our video this week presents a fantastic piece of jewellery from an online auctioneer.

The ladies size 7 ring is composed of 14 karat white gold with a central stone tanzanite surrounded by diamonds of VVS clarity, and is described in detail in the video. It is part of a $2m jewellery collection which is being liquidated.

The video is worth a look for two reasons:  firstly, it offers a rare chance for collectors and investors to get a good look at tanzanite, a rare gemstone only discovered in 1967 in Tanzania. A form of zoisite, it can appear sapphire blue, violet or burgundy according to how the gem is orientated.

Secondly, it's a great illustration for buyers and sellers of high class jewellery of how useful video can be in demonstrating the quality of gemstones, which consistently fails to come across in even the highest quality static images.