If you had opened the link you wouild have seen that HCT is Harcourt, Inc. They are/were the manufacturer of the necklace. (Out of business according to Trademarkia). In my searches I found some stamped Italy and others Canada, like the OP's. There seems to be a bit of controversy with the ones stamped Italy, but from what I can find on other sites and ebay the ones stamped Canada seem to be fine.
So what the OP has is a sterling silver (925) necklace made by Harcourt, Inc (HCT) in Canada.
I did a search. HCT is a trademark as linked above. In my search I found other sterling silver pieces marked 925 HCT Canada listed on ebay, (B)Etsy and the Lane.
I have a Sterling Silver chain that has the markings HCT 925 and Canada on the Lobster Clamp ends. I was under the impression that HCT 925 was Italian made Sterling. What possible reason would there be Canada written next to the HCT 925.