French Police have reported the recovery of a hoard of highly valuable jewellery - which was hidden in a drain.  The jewellery was stolen from a Harry Winston Boutique in Paris just over two years ago, and is thought to be worth €18m.

The daring heist took place in early December 2008.  Four armed robbers - two of whom were dressed as women to disguise their identity - stormed the notable jeweller's shop on Avenue Montaigne in the centre of the French capital, making off with more than €80m of stock.

However, after a lengthy investigation, the Police have located at least some of the stolen jewels.  The 19 rings and three sets of earrings were discovered at a house in the suburb of Seine-Saint-Denis, stashed in a plastic container and set in a cement mould inside a drain.

A Harry Winston diamond necklace worth $1.2m

The retrieval will come as good news to Harry Winston, one of the leading jewellers in the world.  Known for serving celebrities and Royalty, the company celebrates its 80^th anniversary next year and has established a sterling reputation, particularly for sales of unique and rare diamonds.

Only last month, a fantastic Harry Winston 16 carat diamond ring smashed its estimate by realising $662,500 at a Sotheby's auction, which we wrote about here.  And it's not just Harry Winston that has had a good 2011 so far.

Diamonds in general continue to perform strongly; as we reported in January, prices for the precious stones have 'sky-rocketed' over the last three years.  Multiple sales worth tens of thousands have taken place in recent months and there was, of course, the world-record sale of the 'Fancy Intense' pink diamond ring for $45.75m last November.

All this suggests that collectors and investors should consider diamonds an excellent long-term prospect - and you don't have to spend millions to benefit.  Last month's Bonhams sale offered diamonds for a range of affordable prices, and this upcoming Fellows auction has similar selection available.  Much like a beautiful diamond, it's certainly worth a look.