We used to be part of opalauctions.com, their sister site when they had a forum, which I ran for them for quite a few years, and for a few of those years I was also their Gemstone Sheriff, which is why they only verified the photo and description in the ad since they never see the stone in hand; it's up to the seller to be honest so I hope you dealt with a truly reputable seller since those seller ratings are prone to being manipulated on all websites that have seller ratings, and the RRP's given are often greatly exaggerated.
Most of our good articles on the labs came from Robert James, founder of the International School of Gemology, which shut down its forum and moved to FB, at which time the photos that were on their forum and in their newsletters disappeared, but things haven't changed much with the labs so what he says should still be verifiable.
The problem with the labs is that it clearly states that if they make a wrong call, they accept no responsibility for it, and I don't know of any who do accept responsibility for that so if they're wrong the buyer loses even more money.
In the video it appears to be a clean, lightly saturated stone with definite color change, although the candlelight makes it look brownish instead of reddish. It should look better under a Reveal incandescent light which is what I prefer for color-change gemstones. The website says they only allow natural gemstones, but you want that verified too because if the seller isn't a gemologist who tests all his stones, even he could be duped if he's relying on what the person who sold it to him said about it, since lab-growns match the exact atomic structure of their natural counterparts, which is why they will even fool gem testing equipment.
So, since the labs hide behind their disclaimer clause, you might be better off finding a local gemologist and having them take a look at it. They may even give you a verbal appraisal for free, but of course a written one would have a fee, but it wouldn't hurt to ask how much they'd charge to give you their opinion whether in writing or not.
Since I don't use or recommend the labs, I can't say one is better than the other, but we did get word that something like 80% of IGI was bought by a Chinese company some years ago, in case that matter to you.
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Here are two more articles from the ISG on how the labs get around accepting legal responsibility for the bad calls they occasionally make. Thankfully it doesn't happen too often, but when it happens to you you're SOL if the stone wasn't what it was represented to be.
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And you should also be aware of the legal defect in their lab reports because these things matter.
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I'm not so much trying to dissuade you from sending the stone to any lab you choose, as much as trying to make you aware of the problems with them before investing your hard-earned money, and to suggest having it looked at by a local gemologist, especially if the fee the seller charges to have it verified is a bit high.
I hope the information I gave you helps you make the best decision for yourself, and there are plenty more articles in the Labs category that you can access via the Board Index. The ones I showed you are from pages 4 and 5 so you may want to check the newer ones.
So what will you do with the stone, have it set, and if so, in a ring or earring or what? I bought a .35ct alexandrite last year and had it set in a 14kt YG earring that brought the price to what your stone cost.
Let us know what you think of it when you get to see it in hand. It looks like you scored a very nice stone, and I'd say the price was about right for that size, so I hope it turns out to be exactly as the seller represented it to be and you're pleased with your purchase.