Scottish jewellery designer, Ringmaker, plans to open a retail unit in a fashionable area of London as part of its expansion programme. Partners John Gilchrist and Robert Myles are travelling to London this week hoping to clinch the deal.

''We have been after this site for three years,'' said Gilchrist, ''and we have lost out twice already, but this time we are confident we will succeed.''

Ringmaker designs and manufactures specially for each customer, and it is proud of the fact it employs jewellery designers, not sales assistants, in its shops.

''We came up with the idea,'' explained Myles, ''when I was getting engaged, and I got fed up looking in windows at trays of rings which all looked the same.''

The pair started Ringmaker in Bothwell in September 1985. Since then they have opened shops in Glasgow, Edinburgh and Perth.

''We were the first shop to open in Princes Square, Glasgow in November 1987,'' said Gilchrist, ''and it has been a very successful outlet.''

But the London outlet is the one which should transform the company.

Gilchrist and Myles expect it to double their turnover, which they predict will be in excess of #2m within the next 12 months.

The plan is to open a store every year, with Leeds and Dublin being considered. Further down the line, they don't rule out Continental openings.

The concept is to bring personally designed jewellery within the reach of the average High Street customer. A simple silver ring can cost as little as #25, while the average price of engagement rings is #800, although Ringmaker has also designed #250,000 creations.

Until now it has not had a store south of the border even though 10% of its business comes from there. Customers include a former Prime Minister as well as film stars, and sports personalities.

Gilchrist, who studied jewellery designer at Glasgow School of Art and was a visiting lecturer there for a number of years, takes delight in the fact that Ringmaker employs 15 qualified designers.

In addition, there are four goldsmiths in the Bothwell workshop who craft the 10,000 plus rings it sells every year.

''Our rings are designed in front of the customers, who explain to the designer what it is they would like, so that they have a personal input into the design,'' said Myles, who studied architecture before he made the move into the jewellery designing business.