'At Tiffany you are basically paying a massive markup up for a blue box which you can buy on eBay for 25 dollars.'
Worth visited all four luxury diamond retailers with an undercover camera as he claims customers are paying thousands for little more than the brand name.
At Tiffany's, a simple two carat, round solitaire diamond ring with platinum band was selling for $80,000.
At Costco, an almost identical two carat, round solitaire diamond ring with platinum band costs around $19,000.
When Worth compared prices of a basic round solitaire ring, he reported that Tiffany's had a 253 per cent mark up, at Cartier it was 276 per cent, at Van Cleef it is 314 per cent and at Harry Winstone's it is 336 per cent.