The company, which has three outlets in Glasgow and one in Aberdeen, has taken over a 2500 sq ft retail space in the recently revamped Assembly Rooms in Edinburgh.
The 18th-century category A-listed building on George Street is on course to open later this month after an 18-month restoration programme.
Graven Images, which was involved in the design of the Missoni Hotel in Edinburgh, has been hired to lead the fit out programme for Rox.
Work is scheduled to begin in September with the shop open for business by the end of October and ahead of the crucial Christmas shopping season.
More than half of the space will be given over to an invitation-only private shopping lounge, which the company calls a thrill room, and champagne bar which will be similar to the flagship store in Glasgow's Argyll Arcade.
Kyron Keogh, managing director, told The Herald it was a long- held ambition for Rox to open in Edinburgh and it had been working on the deal since January.
He said: "We have been looking for a great space in Edinburgh for quite some time now.
"The locations always have to be right in retail and even more so in these economic times. When we saw the plans for the Assembly Rooms we really got the vision and everything seemed to slot into place for us.
"Units like this don't come up very often and George Street is very competitive right now.
"We are really, really excited about it."
Rox said the expansion is being fully supported by the company's bank, HSBC.
Mr Keogh said: "HSBC has been really supportive. We put together a business plan and they are really behind us in what we are doing."
Rox said its full range of branded jewellery and watches – including Ebel, Frederique Constant, Rado, Raymond Weil, Gucci and Links of London – plus its own designs would be available in the Edinburgh outlet.
It has also received approaches from new brands keen to work with the company.
Mr Keogh said: "Glasgow is so competitive in the jewellery market that there are opportunities with brands which have come up through this move to Edinburgh.
"Brands that we haven't worked with in the past are talking to us and over the year I think we will be bringing on new luxury brands."
Three years ago Rox, which Mr Keogh co-founded in 2002 with childhood friend Grant Mitchell, spent around £1m to open its first store outside of Glasgow in Aberdeen's Union Square Shopping Centre.
In 2010 it spent a further £1m revamping its Argyll Arcade store to extend it from 800 sq ft to more than 4000 sq ft.
The company is expected to report a rise in turnover from £9m to £10m when results from the 12 months to the end of March 2012 are released later this year.
Mr Keogh added: "The performance for 2011/12 was bang on what we predicted and overall we are pretty happy.
"Conservatively we would hope for a 10% increase in sales for the business from Edinburgh but I'm hoping for more than that.
"April and May were difficult but we had a strong June and are around 6% up on a like-for-like basis so far this year."
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