The empress strikes back: Catherine the Great exhibition at the National Museum of Scotland

A new exhibition at the National Museum of Scotland relives the glory of the reign of Catherine the Great of Russia. It's a splendid show with some breathtaking pieces, says Adrian Hamilton

If the German Chancellor, Angela Merkel, keeps a portrait of Catherine the Great of Russia in her study, it is not, one hopes, because of the Russian Empress's expansionist foreign policy or the extravagance of her court let alone the string of lovers she took. It is because Catherine was a German and, more than that, a woman who worked and planned her way to the top and, having got there, used her wits and her intelligence as a woman to stay and reign over Russia's age of splendour for a 34-year term.

Certainly going around the splendid show mounted by the National Museum of Scotland from the holdings of the Hermitage Museum in St Petersburg , what impresses you most – as it impressed her contemporaries – was how matronly she was. As a visitor to the court wrote: "It was impossible not to be struck by her beauty and majestic bearing. She was a large woman who, in spite of being very stout, was neither disfigured by her size nor embarrassed by her movements."

There were portraits aplenty, most of them with the tiresome attributes of a neo-classical art that made play of symbolism and allegory – Catherine pointing to the tomb of Peter the Great to emphasise her debt to that ferocious tyrant who forced Russia to modernity; Catherine receiving the captured standards of the Turks whom Russia twice defeated in the wars, and Catherine as Minerva, goddess of the arts.

But at the centre of it all is a face of warmth and liveliness. There's a copy of a painting by Vladimir Borovikovsky, one the brightest young painters in the emerging Russian school of portraiture that she helped develop, of her walking in the extensive parkland of her summer house at Tsarskoye Selo dressed in plain outdoor clothes, for all the world like a figure from Jane Austen. She rejected the painting as too informal but then she liked, and had copies made as gifts, a head and shoulders by Mikhail Shibanov in later years when she visited Crimea and the new territories conquered by her lover and secret husband, the formidable and bear-like Prince Grigory Potemkin. The portrait disguises nothing of her grey hairs or her portliness but it is of a mature woman whom you'd love to meet and talk to.

She'd had a hard coming of it, of that there was no doubt. Married at 16 to the heir to the Russian crown, the Grand Duke Peter, she entered a loveless relationship in which both partners took lovers. She was there to provide an heir and, when she did, was thrust aside again. As she recalled in her memoirs: "Finally toward noon, I bore a son... the Empress Elizabeth had her confessor come and he gave the child the name Paul. The Empress immediately had the child taken to a midwife. No one had thought about me. I was dying of hunger and thirst. Finally I was put in my bed and did not see a living soul the whole day."

The isolation lasted 17 years, during which time she learned Russian, made friends, read widely and prepared for the day the Empress died. When it came in 1761, she was ready. Her husband, part-educated in Germany, lost support by being too much in awe of Russia's enemy, Frederick of Prussia. His German wife gathered support by being seen as wholly Russian in her sympathies and her new Orthodox faith. Barely more than six months after he had become Emperor, Peter III was deposed and Catherine made Empress in 1762. A week later he was dead at the hands of the brother of Catherine's lover at the time, Count Grigory Orlov.

It's a sign of the times that the Russian art establishment could promote an exhibition like this, on the 250th anniversary of Catherine's accession. The shows calls her "Catherine the Great: an Enlightened Empress", which is pushing it a bit. Although Catherine set out to be a model ruler in terms of the Enlightenment, sought the friendship and advice of Diderot and Voltaire (both of whose libraries she bought) and wrote a provisional draft constitution, she soon backed down when the strength of the opposition from nobility and landowners showed itself. Serfdom increased under her long reign as did the privileges of the nobility.

What she was, and what the Hermitage clearly glories in, was a German turned Russian nationalist determined to show that Russia, through patronage of the arts as much as conquest, was the equal of any in Europe. Nothing was spared in the effort. Like a modern-day oligarch, Catherine had her agents scour Europe for old masters and new commissions for her palaces and new arts foundations. Just as Peter the Great had done, she brought in architects, artists and artisans to glorify her court but also to teach the Russians to produce the same. Porcelain, tapestry work, gemstones and ironwork, all found themselves encouraged with new factories and an assured imperial market.

The exhibition shows a comprehensive, and thankfully not too excessive, selection both of the work of the foreigners brought to St Petersburg and the local manufacture. Porcelain is very much to the fore. Catherine received it as gifts from France and Germany and gave it in large dinners services to her favourites, bent on making Russian imperial porcelain as great as Sèvres and Meissen. On the evidence here, Imperial Porcelain never quite matched its European models, although a wonderful Wedgwood service keeps up the British end. If you're looking for what was special about Russian craft it lies more in the glass and in the metalwork, of which there are some breathtaking examples.

In it all it is difficult to define precisely what was Catherine's own taste. Rational as she was, she preferred the new neo-classicism to the old Baroque or, in later life, to the new Romanticism. A charming portrait in the show of her two granddaughters by the French artist, Elisabeth Louise Vigée Le Brun, in the new sentimental style she dismissed as making the young girls look like "pug dogs" and "repulsive little French peasant girls". She had no ear for music, no discernible taste of her own in commissioning pictures. But she was passionate about architecture and interior decoration. Building, she declared, was a "diabolical thing. The more one builds the more one wants to build, it is as intoxicating as drink." Curiously for modern taste, she also had a passion for cameos, old and new, building up the largest holding anywhere of "tassies", copies of medallion made by James Tassie in London.

She managed men as Elizabeth of England had done: with care and to purpose. She balanced the forces of the country with great skill and she brought up her grandchildren with fondness. She was known as "mamuschka" or "little mother" in Russia, just as Chancellor Merkel is called "mutti" or "mum" in Germany today.

Catherine the Great: an Enlightened Empress, National Museum of Scotland, Edinburgh (nms.ac.uk) until 21 October