Dear Enigma,

It really depends on what you mean by “natural sapphires”. These are not man-made or synthetic sapphires. So, in that sense, you could say they are natural.
However, they are treated. And by treated, I don’t mean heated sapphires which is an industry-accepted treatment method. Most of the sapphires on the market are heated.
These sapphires here, instead, are what is called cobalt-lead glass-filled sapphires. They are also called lead and cobalt glass filled sapphires, cobalt-doped glass-filled sapphires, or cobalt-doped composite sapphires. In essence, these are composite sapphires.
A very low-quality starting material is used – opaque, industrial-grade stones. It is then mixed with powders that contain lead and cobalt. This mixture is heated fusing the powders into a cobalt-lead glass that penetrates the fractures and cavities in the stone. Lead-cobalt glass can account for most of the stone’s weight.
Basically, the technology is pretty much the same as that used for the lead glass-filled rubies. The main difference is that for the cobalt-doped composite sapphires, as the name suggests, cobalt is used.
These composite sapphires have the same durability problems as lead glass-filled rubies do. And yes, they are almost worthless (just like lead glass-filled rubies).
£137.79 (ca. $179) is definitely not a good price for this bracelet. You can easily buy alike bracelets at a price around $40 – $60 on eBay (note: at auction, not “buy it now” format). So, this price here is 3 to 4 times higher than what would be reasonable for a composite sapphire bracelet.
You can read more about composite rubies (in order to better understand issues related to composite sapphires) here:

Lead Glass-Filled Rubies: A Perfect Waste of Money

4 Easy Tips on How to Identify a Lead Glass-Filled Ruby

Arnold,

I do understand you. This kind of situation can be really frustrating. I agree with you that the auction site should step in and facilitate the return and the refund. You mentioned that they keep the money for two weeks. Is the auction site in question Catawiki? I know that they would hold all the payments for two weeks. Anyways, this system is designed to boost trust in the buyers, to make them feel safer, more protected. And if it’s not working to your benefit in a situation like this, then what’s the point to have it in the first place?
What they are saying about private sellers (non-business sellers) is true. The EU law with its right to cancel and return your order within 14 days does not apply here. However, this situation here has nothing to do with the EU law. I mean, the auction house (auction site) can have its own policy in place in order to protect its customers. It wouldn’t be against any law to expand this coverage so that private sellers’ customers are equally protected. And that would be very easy to do as long as the money is still in their account. So, there is no excuse for them not to do that. Except that they are not interested in that. It is bad for the business, I mean. They would rather earn their commission on this sale, and you are left with all the losses.
So, I would suggest you try to convince them that it is their obligation to step in and to protect your lawful interests. However, if it is already too late (they don’t have your money any longer), or you do not succeed in convincing them, here are a few things I’d suggest you give a try:
1. Check whether this seller is selling a lot of items. I mean, does it look like he/she is selling personal belongings from time to time or is it rather a business activity aimed at gaining profit? A lot of private sellers are not really private sellers within the meaning of the law. They are selling a large number of items on a regular basis and for profit. As a rule of thumb, they are not paying taxes. So, it might be a good idea to tell them that if they wouldn’t go for a refund, you might contact their tax authorities and pass on the information concerning tax evasion. I think this is by far the best approach. It has helped me several times actually.
2. Tell the seller that you would contact the police. As you rightfully noted, it can be regarded as fraud if there are serious discrepancies between the description/images and the actual goods. If the seller was from China, this wouldn’t help, but as the seller in question is from the EU, there is a pretty good chance he might reconsider his position.
3. Tell them that you have a powerful blog (e.g. for collectors of antique furniture) with millions of monthly visitors and you will start writing about them if you don’t get your refund. Tell them that in the long run this would hurt them much more than this single refund.
Let me know how did it go!

Anna is absolutely right on this – it is dyed beryl. This is the way it goes – they (manufacturers of these items) take low-quality beryl (usually white) and dye it with green color. When it is dyed, it is impossible to tell what the initial color was. Now it is green and it is beryl. As you may know, green beryl is called emerald. However, not when it is dyed. They can call it whatever they want, but it is nothing more than cheap, dyed beryl after all.
What amazes me is that Catawiki’s “experts” keep on accepting and listing these items for years. And they allow labeling these items as emerald necklaces, bracelets, etc. Could it be that they don’t know what it is? Possibly, but then they are no experts. Could it be that they do know what it is? Possibly, but then they are fraudsters.
This listing made me laugh. Through the tiers, though. Catawiki auction site proudly presents itself as listing only unique and special objects. They say they have professional experts vetting every submitted item. They say all the auctions are supervised by a notary public. And they do not allow to use stock images in the listings. What a shame! What a shame when you compare their words and actions! Here is the original listing of this item on eBay (with the same images :)): https://www.ebay.com/itm/Green-Emerald-1161-50-Cts-Earth-Mined-4-Strand-Round-Shape-Beads-Necklace-Rare/362439204534? (just in case this listing gets removed by eBay, I attach the screenshot here, too).
So, to cut the long story short, I am happy for you, Martin65, that you didn’t bid on this item. I have no intention to say that everything is fake and bad on Catawiki, but you have to exercise due care because most of their “experts” are good for nothing. Or they are instructed to close their eyes to many things. Who knows…