Making a record one-off sale is still something to crow about in the beleaguered retail sector.

So Kyron Keogh and Grant Mitchell are quite rightly smiling when they tell the tale of the £50,000 diamond ring sold in November by the Rox jewellery chain they run. But there's a satisfaction beyond the price tag and setting a new marker.

Mr Keogh said: "This was a customer that had not shopped with us before, didn't know the Rox brand and had been around the world looking for the right thing.

"They'd been to Tiffany in New York, all round Dubai and all over Glasgow.

"It wasn't about the price. It was about us getting them what they wanted and making them feel special.

"We went the extra mile and sourced the best product we could which got us the sale."

With Christmas sales expected to be around 6% up, helped by a 27% jump in online transactions, the company is on course to break £10 million in turnover.

Keogh and Mitchell have come a long way since meeting and becoming childhood friends while on holiday in Majorca.

The carmaraderie between them has survived flat-sharing in London, growing families and a decade together in business.

It perhaps helps that they both bring different things to Rox.

Mr Mitchell, a father of three who lived in Glasgow, is the entrepreneurial jeweller having started out in the Argyll Arcade, spent time on a stall at Camden Market in London before coming back to Glasgow and starting the Lewis Grant diamonds business.

Mr Keogh, who has two children, with a third on the way in June, also lives in Glasgow and trained as a chartered surveyor. He went to Hong Kong as a management consultant then sold a software company in the dotcom boom. He tends to focus his energies on operations and management.

They look relaxed sitting in the so called "thrill-room" on the first floor of the flagship store in the Argyll Arcade in Glasgow.

It's a bright space with large mirrors, wooden floors, plush rugs, films projected on the wall and a bar in the corner.

If you transported the site to a trendy boutique hotel it wouldn't feel out of place, which is apt given the company responsible – Graven Images – also did the Blythswood Square Hotel.

Transforming the space was a key part of a £1m refurbishment of the Argyll Arcade shop towards the end of 2010. One of the drivers was a desire to give customers a better shopping experience, but the opportunity to host small-scale events was also high on the list.

So alongside themed evenings around weddings and Valentine's Day there been some higher-profile gatherings with racing driver David Coulthard and singer Emeli Sande.

Mr Keogh said: "People are feeling the spending squeeze and we want to reward them for their business. But we are seeing proper bottom-line benefits from these events as well.

"We saw a real increase in sales of TW Steel watches following the David Coulthard event."

The impact of the investment in the store is also paying off on a day-to-day basis.

Mr Keogh said: "When a customer come into the shop we want them to feel like an A-list celebrity and give them that real rush of having a special experience whether they are spending £20 or £20,000.

"During the week this space is relatively quiet, but come the weekend it is buzzing with couples buying engagement rings and guys getting down on bended knee."

Mr Mitchell adds: "The other thing is people want privacy when they are buying engagement rings. They don't want their friends walking past the store and seeing them. With this space we offer a bit of privacy away from the street level."

Alongside the downbeat economic environment, rising diamond and gold prices have affected margins.

As a result Keogh and Mitchell are cautious on prospects for 2012, although they have a number of options which they believe will grow sales.

An online database of diamonds is being launched shortly which will allow people to choose stones and then have a ring commissioned.

Mr Keogh said: "We looked at the example of Blue Nile in the US, which is an online diamond retailer which has experienced big growth.

"We dipped our toe in the market a few years ago but it wasn't quite mature enough. We think it is now mature as we are regularly selling £3000 and £4000 diamond rings online. It's been a project which has been going on for a long time and we want to make sure we can deliver.

"There's not any value in having an all-singing, all-dancing application which doesn't work."

Mr Mitchell said: "When people spend a lot of money they want to trust who they are buying it from. Jewellery is really all about trust as we are recommending this is a good diamond.

"There are certificates now, which help. It's all very well looking at these, but if you don't know what they mean you still need that reassurance."

Another plan is to develop Rox's own silver brand which became a popular seller over the festive period.

Initially it will be through sales in the four Rox shops, but Keogh and Mitchell are tentatively looking into wholesaling the range through department stores, other jewellers and online retailers.

Developing other luxury goods such as leather, scarves, garments and candles is a more long-term aim.

Mr Keogh said: "We have to take one step at a time, but there's a lot of potential. We are operating in the luxury brand arena, but we need to have a broad offer in order to drive growth and increase market share."

Beefing up the in-house brand also gives the company greater flexibility should it decide to open more shops.

Mr Mitchell said: "Our biggest problem for expansion is getting the brands to come with us to the shopping centres we want to get in to. If we wanted to go into Manchester a lot of the brands we do well with are already taken by jewellers there or have their own stores. So in order for us to go into these places we need to have a very strong Rox offering.

"All these different gifting lines and having our own offering will make it easier for us to grow more rapidly. It is a great way to get your brand out there."

However, there's a recognition the business environment is not conducive to the capital-intensive process of opening up new stores.

But Mr Mitchell is looking on the bright side. He said: "As time goes on things will ease and funding will become more readily available for expansion.

"When that happens we will have done all the homework to get us ready."

2002 Rox is founded with its first store in the Argyll Arcade in Glasgow.

2004 Braehead shop opens.

2007 The business expands with a store at Silverburn.

2009 The opening of the £1m Union Square shop in Aberdeen marks the first Rox outside of Glasgow. The business is named independent retailer of the year.

2010 The flagship Argyll Arcade store undergoes a £1m refit and is extended from 800 sq ft to almost 4500 sq ft.

2011 A £25,000 investment optimises the online site for use by mobile devices. Rox named retailer of the year at the Scottish Fashion Awards and independent jeweller of the year at the UK Jewellery Awards.

2012 An online diamond buying and bespoke ring commissioning service is launched.