OP, I can understand your concerns about believing everything AI and Google tell you, but having Googled it myself, I think it's pretty clear that you DO have rights under the 'Consumer Rights Act 2015', however, if you want to be sure, contact Citizen's advice. This is what I picked up on:
Yes, your rights are exactly the same. Under the Consumer Rights Act 2015, buying a physical item inside a retail shop gives you the exact same protection regarding faulty, damaged, or poor-quality goods as buying online.
The only difference between buying online and in-store is for "change of mind" returns. Since your ring has a deep scratch and is not of satisfactory quality, the law treats it as a product fault, and your in-store rights are fully protected.
It seems that in the first 6 months after purchase, it's on the jeweller to prove that the ring was not damaged before you purchased it, rather than the other way around.
It also said that you can shut down the argument about knowing that all gold scratches easily with the following:
"While I understand 18-carat gold is a softer alloy, a reasonable consumer expects a brand-new ring to withstand three hours of normal wear without sustaining a deep scratch. Gradual wear-and-tear is expected over time, but a deep gouge within hours points to a pre-existing defect or a lack of satisfactory quality at the time of sale. Under the Consumer Rights Act 2015, the burden remains on you to legally prove that this damage was caused by abnormal impact or misuse during those three hours. Otherwise, I am fully within my short-term right to reject the item for a full refund."
If all else fails, assuming you paid on a Credit Card, claim back through them, but I really wouldn't totally discount Google's response to this situation.