ERIC N Smith Limited is celebrating 25 years in the jewellery business, with a level of renown and success which could never have been anticipated when Smith started art school 30 years ago and began producing his first designs.

The company is recognised country-wide for the style, quality and service which it brings to the business. This is emphasised by it supplying more than 100 selected outlets in the UK, including many in Bond Street in London.

Within Glasgow itself the showroom in Newton Mearns has been in operation for over 18 years, and customers travel to it from far and wide, secure in the knowledge that everything is produced in-house from the finest quality materials.

As a designer, Smith knows precisely how the finished product will come alive, and is familiar with all the processes necessary to make beautiful jewellery. The company also employs four goldsmiths to produce the designs, and they in turn know every aspect of the work involved.

Early in the history of the company Smith's wife Yvonne became involved, and where he is a natural designer she is undoubtedly a born saleswoman. One of the main ideals of the company is for all staff to be aware that listening to customer requirements is an essential, and Yvonne has always found her response to this to be practically intuitive. ''She knows exactly what people want,'' says Smith, ''and she always has a real instinct for being able to understand concepts immediately.''

The needs of the customer were to the forefront of their minds last year when the Smiths decided to branch out from their premises in Newton Mearns and open a new shop right in the heart of Glasgow.

This new showroom at 111a West George Street aims to serve the centre and north side of the city. Aware that many customers had travelled citywide for years for the exclusivity of his jewellery, Smith had felt it was time to make the business even more accessible. It has undoubtedly made life easier for many customers, especially those who work in the city, and has introduced many new clients.

The window displays in this new showroom are very appealing, with an arrangement of eye-catching pieces. But the real impact lies inside. The interior has an air of luxurious simplicity, with stunning displays and the most extensive range, not only of jewellery but of silverware, porcelain, pens and enamelled boxes.

It feels as if everything is out front, to be studied and admired at leisure, complemented by the sight of the goldsmiths working away in full view of customers and window-shoppers.

However, that apart, as a company Eric N Smith Limited has long been recognised as a name in diamond jewellery. Smith has been awarded the UK jewellery industry's ''Oscar'' in 1993 as Designer of the Year, in 1994 for Best Design in Diamonds, nominated in the finals in 1995 and again this year for Best Design in Diamonds. There is a tendency to think primarily of engagement rings when considering diamonds, but the Eric Smith Collection displays a superb range of settings for this precious stone.

Pendants, earrings, and eternity rings provide an equally perfect backdrop, and the versatility of the stone is such that the setting can be varied according to taste. A perfect diamond seemingly resting lightly on the most delicate twists of gold can have the same impact as one set firmly on a much more solid background.

When it comes to individual requirements, Eric N Smith Limited is confident of satisfying any client request, not least because of its ability to buy from source. This enables the company to supply customers with anything from the smallest and simplest of diamonds, right through to stunning stones several carats in weight.

While this level of service is familiar to clients of many years, the surprise for the new customer lies in the sheer size of the operation. This is one area where the solution to the perfect gent's gift is literally in your hand.

Christening gifts are complemented by corporate gift and presentation pieces, which is extremely convenient in this particular location, surrounded as it is by so many businesses.

The resident craftsmen can manufacture special orders, and execute restoration work, remodelling, and repairs. Valuations for insurance are a large part of the business, providing an accurate description of both jewellery and silverware. Valuations can be written in a couple of days.

The showroom also has an extensive stock of ready-to-wear diamond jewellery, which reflects the modern classic image. Cultured pearls are always popular, as are Italian gold chains and a large range of earrings from the simplest gold studs to diamond ''headlights'' that will flash and dazzle. There are so many occasions in life which can be enhanced by a gift of quality, and Eric N Smith is extremely experienced in helping the customer choose the ideal piece.

Exciting diamonds which are a bit out of the ordinary have a timeless appeal, irrespective of their presentation. Throughout the company there is a prevailing sense of the occasion and celebration which is so often a part of buying jewellery, and it is this constant professionalism which has ensured the ongoing success of the company in Newton Mearns.

The same attention to detail is apparent in the new showroom at 111a West George Street, and the 25-year celebrations can only be enhanced by the knowledge that this company is going from strength to strength.