If you enjoy the thrill of the chase and love a bargain, then eBay and the markets are the place: low-budget, high adrenalin and still the occasional amazing find (although most dealers now research their wares and know how much to sell for).
The USA is the breadbasket of vintage simply because its size and consistent affluence during the 20th century means that there is still an apparently unending mine of pieces turning up - that's what makes eBay such a great hunting ground. At auctions online and in the real world, bidding for a lot that contains multiple pieces is a great option: it's a lucky dip, but you can end up with unexpected treasures that are even better than the original piece that caught your eye.
If you are looking for a one-off statement piece to go with a specific outfit, such as a 1950s parure for the Mad Men look, or some 1930s Bakelite, and you don't mind spending a bit more, trusted vintage fashion stores often have a selection of good jewellery that chimes in with their aesthetic. For example, the online vintage boutique Atelier-Mayer.com has a large collection of vintage designer mid-century costume jewellery including pieces by Chanel, Lanvin and Schiaparelli.
Dubai's La Belle Epoque Jewels (050 927 6400, www.labelleepoquejewels.com) sells pieces ranging from the 18th century to the 1960s, through private viewings and appointments. Owner and gemologist Carrie Ryan selects all the pieces herself - each independently certified and valued for insurance purposes - and can help find you something to match your requirements.
The great jewellery sales at Christie's (04 425 5647, www.christies.com) and Bonhams (04 344 9945, www.bonhams.com, see below) offer some exquisite precious pieces and you can buy safe in the knowledge that everything is certified and valued by the world's top experts. You won't get a bargain but you're unlikely to pay over the odds unless you find yourself in a battle with another bidder.
If you love Mughal jewellery, now widely collected, the legendary Gem Palace in Jaipur (www.gempalacejaipur.com) is an essential starting point - as royals, rock stars and Hollywood and Bollywood actors already know. You might not buy but the quality of the pieces there will give you a standard to judge your purchases against.
If you do want to buy precious or prestigious pieces you would be well advised to start small; research extensively and develop your eye before you take the plunge. If you're paying Dh500 it's no great shakes but there are plenty of paste "diamonds" and cultivated pearls out there pretending to be something they're not.