However, I did a bit of digging around a while ago and was rather surprised to find quite how much profit some jewellers are piling on to plain gold wedding rings.
I picked wedding rings since they are much easier to compare like for like than engagement rings. Each diamond is unique and has its own grading, so it would be easy for a jeweller to claim that their diamond was a better quality than one for half the price at the shop next door.
With plain gold rings, it's much harder to claim there is any difference in quality, since it is a natural material which can be melted down and reused. The only slight complication is that 18 carat and 9 carat gold is made up of gold and other materials, but I worked out that the other materials in a typical 18 carat gold wedding ring would be worth about 20p. It's the gold which made up the bulk of the value.
My search involved looking for as many gold rings as possible which also gave a weight in grams. I found several kept that material hidden - it was actually many of the cheaper retailers which were happy to share the information.
At the time of searching, gold was valued at £28 per gram.
The cheapest jeweller I found was a 'refurbished' gold wedding ring seller on eBay, which was offering a 3.64 gram ring at £149 - the equivalent of £54 per gram, or about twice the raw material market price.
If you wanted a ring which wasn't refurbished, another eBay jeweller was offering a ring at the equivalent of £64 per gram. Amazon wasn't far behind, with gold wedding rings selling for the equivalent of £68 per gram of gold (£189 for a 3.9 gram ring).
Purely Diamonds, which is a well-respected independent online jeweller was a little bit behind, with the price working out as £77 per gram of gold (remember the market price of gold at the time was £28, so that's a markup of about 2.5 times).
A typical high street jeweller was quadrupling the value of the gold, with a per gram price which worked out as £114 (that was Fraser Hart, but others were along the same lines).
Finally, we looked at Cartier, which worked out as £263 per gram of gold.
That's a markup of 841% by my calculations.
Now, of course you can always argue that buying from Cartier offers a completely different buying experience than buying a refurbished ring from eBay. It does, that is certainly true. No doubt they offer a personal service, all the advice you want, plus the ring is engraved with a fashionable name.
I don't think there's a right or wrong in this, but if you are planning a wedding on a budget and looking for corners to cut, I would certainly consider buying a cheap gold wedding ring - you can save yourself hundreds of pounds on a product which is essentially the same as the luxury version.