Well, this is how it happened.
It was in an antique retail jewellery shop in Paris. The stone was on a setting (ugly one). The seller estimated the weight to approximately 0.80 ct, according to the length and width. He couldn't measure the depth due to the setting. Then the price was settled for the stone. I was hesitating, because I was rather looking for about 1 ct. So the man decided to unset the stone immediately, on the spot. Then we weighed the stone and it turned out to be 1,15 ct... but he kept the same price. So I didn't hesitate anymore, although the culet is really deep and consequently the stone looks rather smaller, from the top.
No lab graduated this stone, the colour is my estimation according to the many stones I have already seen (but I know I may be mistaken). I am a french gemologist. I think in France stones are rather underrated compared to USA.