Seriously though, for that money, I'd want an independent grading & assessment done. Like the EGL, TGGC is not truly unbiased; it's a commercial entity. Fine for normal, more workaday stones and jewellery where their certificates provide a bit more certainty than the mass-produced fakes out there, but when you're talking of truly investment grade prices, cold hard reality outside the "Gemporia bubble", to quote Emily, has to kick in. For example:
- Is it really "AAAA"? What's your own understanding of what that means? Is it the same as TGGC's? Personally, 4A can only be for truly trichroic Tanzanite; blue, purple and red, like top Uruguayan, Siberian or Zambian amethysts. Saturation and size/weight are not good enough. TGGC messed in their own back yard when they started qualifying their A grading of Tanzanite with the words "clarity" and "colour". At £20K - or even £7K - it has to be AAAA on every level, which leads me on to...
- Cutting. Here it makes all the difference. Can't stress how important this is for gems in this price bracket. A bog standard oval or pear brilliant won't cut it
. You'd want to get the stone quality assessed by a master cutter/gem "doctor". One mis-aligned, inaccurate facet hidden away on the pavilion can affect the price massively.
As Qwerty123 said, not really sure you'd be spending that sort of money on Distance Selling Regulations and TGGC's T&Cs, unless you're eating fois gras and chips on a Friday night, followed by a big fat cigar of Bullseyes.