Hello. I have been reading many posts about sapphires. I currently have a natural unheated sapphire that was sent to me from a company to look at. While the color is a beautiful cornflower blue cushion there are many angles where the stone goes completely colorless... in certain lights it looks clear even from the top but other times it only looks clear from some side angles. Is this how all unheated sapphires are? I have to decide in the next couple of days if I should buy it. Again, the color (when there is color) is absolutely beautiful but the lack of colors, in some lights this is quite significant, is a concern to me. Any advise or insight would be greatly appreciated. Thanks so much! 