Recently we had the privilege to have an empassioned presentation on coloured gemstones - how to buy wisely and how to invest.

Tony Diniz was the presenter, who positioned himself modestly, but is the leading gemstone dealer in the world, supplying hundreds of millions of pounds worth of gems to the likes of emirs, royalty, Chopard, Tiffanys, Piaget, HStern as well as the mass market like QVC (US). A native Brazilian, but now a major global player, Tony effectively "controls" the market for a number of precious stones. He charmingly described himself presenting to "the most beautiful audience" he had ever encountered. As much as Tony was dazzled by the audience, so were we by the jewels one of our members/team, Paola Bradley, brought in from the private collection, that Tony has helped her to collect. This served to illustrate key points to look for, and avoid, when buying coloured stones, rare commodities with imperfect market information.

Diamond prices are well documented, so the potential to make margins are small, perhaps 15%. After Angelina Jolie sported massive emerald earrings at last year's Oscars fashion echoing the market's interest in coloured gems has increased. Just this week, the 2010 Oscars saw Kate Winslet adorned in a $2m Harry Winston necklace with a huge coloured central gemstone.

Perfect rubies and sapphires are hard to find and the country of origin and mine can make a significant difference on value. Tony prefers to steer clear of these with the exception of one rare sapphire. It is a deep peach toned pink sapphires from the rare padparadsha mines that command premium values. We were warned of stones being called Padpadrasha "coloured".

Tony talked about the highly prized Columbian emeralds that are more value the less inclusions they have, contrary to sales patter about "the jardin" of imperfections enhancing colour. Paola demonstrated some BT "Before Tony" and AT (after Tony) pieces to demonstrate the difference.

AAAA Tanzanite and the highly prized, no longer mined neon blue and green Paraiba Tourmalines and Mutuca Indicolite - the holy grail of the gemstone world as well as other priceless sparkling specimens were discussed, the things to look for and avoid, and examined, and tried on (!), with keen interest.

Tony stressed that to buy jewels first for love, next buy smart, over 1ct, for most gems, flawless, if set in jewellery then only buy platinum or 18ct gold, to ensure you are getting the best price. He made an offer that any he will source any particular gem Addidi friends want and set it in a bespoke jewellery piece for 30pc of his cost price. This is likely to be 10 to 30 times less than the retail value.

For a gem to be an investment, you need to have a buyer! So Tony talked about three investment projects he and Paola are working on. First, is a "Gem Bank". Tony has business interests in a number of retail outlets, guaranteeing a constant demand for stones. Rough stones are bought in parcels of $300k-$500k. The time from rough it takes for the rough stones to be cut, polished and jewellery set, takes 6-12 months. Instead of borrowing from a Brazilian bank at a very high interest rate, Tony will pay a monthly 1% interest and a generous percentage of annual profits. The second, proposition is to participate in raising $5m for a 30% share in a business that will float for a minimum of $200m within 3 years of launch. This has been proven twice elsewhere in the world, with similar customer base. The third, The Addidi Jewellery Club, proposition is to invest in a prestige fractional ownership collection.

It's questionable whether Tony or the collection was the star of the show. The former had a Brazilian twinkle in his eye; the latter just twinkled!

Contact details - If you are interested in finding out more about the propositions mentioned in this article, then please contact Addidi in the first instance.