When did you first fall in love with the idea of making jewellery, Glenn?

It was when I was 18 and I made my first engagement ring for a friend. I realised I must have done something right because both he and his fiancée were smiling when they saw it, and he handed me a cheque. I thought, ‘How exciting is that?’.

Why did they entrust you to make such a special item?

I was an apprentice at Cartier’s workshop. The guy called me, said he was getting engaged, said he didn’t have a lot of money and so on, and I said I’d do it. I made it, put it in a little box and I remember the two opening the box and just sitting there with a big grin. I realised then that I could make something nice, make people smile.

What did you do next?

After an eight-year apprenticeship in London I opened my first workshop when I was 22 with a friend. We made wonderful jewellery for Mappin & Webb, Garrards, Asprey and other big houses.

What’s a typical day for you?

Well, for a long time now I’ve been sourcing and collecting rare and exceptional gemstones and turning them into wonderful and predominantly one-off creations. So my day involves calls from people all over the world wanting to see if I’m interested in a stone or stones they have. I’ll come in to the atelier, check some stones, sit with the team and think about pieces we will be making. I’ve clients coming in periodically for a private chat, and very often I fly to Geneva to our workshops to speak to the production team and check first-hand how things are progressing. In truth, it’s not such a bad life, especially when having lunch in Mayfair or Geneva, overlooking the lake.

What is it about fine jewellery that you find so mesmerising?

Actually, I do not love jewellery; what I do admire and have a passion for is truly wonderful jewels and gems, new and old, but these are few and far between. There are discerning buyers who take time to find a real jeweller and they work with them. I like to think we come under that bracket.

Is this band of ultra-discerning clients pretty small?

Well, we’re a private house and we have a select group of private clients. We take a lot of time when we buy our stones. We cut them, we work with them – they can sit around for years and years until we get a little bit of inspiration to make something.

How do you go about designing something?

There’s no rhyme or reason. What we try and create is something that really is out of this world. It’s like artwork, really, something special. It’s not just a diamond on a chain or a collection, and I know it’s right for a client when they come in, see a piece, and get a silly smile on their face. I say, ‘You know what, you’ve got the same silly smile I had when it came out of our workshop.’ That silly smile is what I enjoy the most.

What’s the longest someone’s taken to decide they want to buy something with a price tag in the millions of dollars?

It’s going on right now – three months. The client has asked me to be patient and I am.

And the shortest?

I bought something that had great value, was super-rare, I sat it in the simplest blue titanium ring that took about an hour to come up with, and as I was walking out of the office I called a friend and I said to him, ‘Are you rich?’. He said he was, and I said, ‘OK, I’ve a stone for you’. He said, ‘Alright, I’ll have it.’ It was in the tens of millions of pounds.

Is there an underrated gemstone that you think deserves more credit?

I love Cognac diamonds. They are so chic and so special; I think they are extremely elegant and wearable.

Is there a different period in history you wish you’d been doing what you do?

I don’t think so. Maybe the 40s and 50s, because I quite like that period, but I wouldn’t like to go back too far – I like the luxury of the amenities we have today.

Do you have clients in the UAE?

I do, and when I go to the UAE or they come here, I find the people charming. I find that, increasingly, they have travelled and studied in Europe or America and they have become very discerning about what they want. And they want to be different – they don’t just want to walk into a shop or buy a brand, they want more than that. They want a one-off.