People often ask me what makes one piece of jewellery more desirable than another.

Sometimes they're expecting me to say it's the size of the diamond or the age of the piece. More often than not, it isn't either of those things.

Having spent years buying, selling and sourcing fine jewellery, I've learnt that the pieces people come back looking for tend to have a few things in common.

It starts with craftsmanship

The first thing I notice isn't usually the carat weight. It's how well the piece has been made. The finish, the way the stones are set, the proportions, the attention to detail. Those are the things that separate exceptional jewellery from jewellery that's simply expensive.

It's one of the reasons I love the great jewellery houses. Cartier, Boucheron, Tiffany & Co., Van Cleef & Arpels and Bulgari have built their reputations over generations, not because they follow trends, but because they consistently produce beautiful, well-made pieces.

Rarity is often more important than age

People are sometimes surprised when I tell them that an older piece isn't always the rarer one. I've handled jewellery that's over a hundred years old which appears fairly regularly, and I've also spent months trying to source a modern piece that was only made for a short time.

Limited production, discontinued collections or unusual gemstone combinations can all make a piece far more sought after than its age alone would suggest.

Condition can make all the difference

This is something I talk about a lot because I see it all the time. Two rings can look almost identical online, but once they're in your hand, they're completely different.

One may have been lovingly cared for, with crisp hallmarks, original stones and very little wear. The other may have been heavily polished, altered or repaired over the years.

To most people they look the same. To someone who buys jewellery every day, they don't.

I always like to see the original box and papers

Are they essential? No. Do they make a difference? Very often, yes.

They help tell the story of the piece and give confidence about its history. It's a bit like buying a classic watch or car; having everything that originally came with it is always a bonus.

Some designs never really go out of style

One of the things I enjoy most about my job is seeing which pieces people continue to ask for, year after year.

Certain Cartier collections. Tiffany classics. Iconic Van Cleef & Arpels designs.

Trends come and go, but some pieces have a timeless quality that means they're just as desirable today as they were when they were first released. Those are the pieces I get excited about finding.

So what makes jewellery truly collectable?

For me, it's never just one thing. It's the craftsmanship. The condition. The rarity.

The story behind it.

And perhaps most importantly, whether it's a piece people will still be searching for ten or twenty years from now. That's the standard I use when I'm buying for Luminary.

If I wouldn't be proud to own it myself, it won't make it into the collection.