When the skies are grey and the streets are frozen mud, what you need is bling - gold, silver, platinum, precious gems and pearls. Luckily the Kremlin museums are heaving with jewellery this month: you can see the treasures of the Mughals in the bell tower, catch Tsar Alexei's orb in the Patriarch's Palace and inside the Diamond Fund peer at the Russian crown jewels in their darkened vault. When you've recovered from all this, you can visit the geological museum across the road for geodes full of amethyst, glossy malachite and starry quartz. Buy a ticket at the Kremlin's entrance tower in the middle of Alexander Gardens. There are several options: the best bet is the "architectural ensemble" ticket which is 350 roubles and covers the temporary exhibitions. You will need to buy a separate ticket inside for the Diamond Fund, which costs 500 roubles. The whole complex is closed on Thursdays.
Going in through the main entrance across the bridge, you pass between the canons of the Arsenal and the glass and concrete Kremlin Palace concert hall. A back entrance to the Patriarch's Palace leads to an exhibition (which ends next Sunday) of Ottoman treasures drawn from the Kremlin's vast collections. Besides the gold and rubies, the chasing, carving and enamelling, there are materials here that you usually only read about: damascene and tortoiseshell, turquoise and sapphire.
The "Ivan the Great" bell tower is through the archway into Cathedral Square. In the exhibition room at the foot of the tallest tower, you can see the "Treasury of the World". This title is taken from a report by the first English ambassador to the court of the "Great Mogul", describing how Shah Jahangir heaped up rich stones "as if he would rather build than wear them". Organised according to decorative techniques, there are examples here of all the "jewelled arts of Mughal India". If you feel a yearning for emerald-encrusted turban ornaments or enamelled katar daggers, this is definitely a must-see. There are also individual gems big enough to be engraved with verses from the Koran or the names of the emperors who owned them. One of these is Shah Jahan, who built the Taj Mahal and whose name in Persian means "Ruler of the World".
Once you have finished with the Mughals, there is nothing to stop you strolling round the gardens and the outside of the cathedrals. If you are lucky enough to catch a sunny day, the light of the 30-odd gold domes can be dazzling. If it is overcast, the Diamond Fund will brighten your day. Turning right between the walls and the Great Palace, you reach the Armoury and a door marked "Almazny Fond". Just ask the guard to let you in, buy a ticket and leave your coat and bag in the Armoury cloakroom. When you finally enter the two rooms that comprise the publicly-accessible portion of the Finance Ministry's treasure hoard, it may seem disappointing. You start with some raw gems, heaps of brilliants and cases of elegant modern jewellery to warm you up. The interesting historical items are still to come.
The lumps of gold that dominate the centre of the first room have their own darker history. Light-heartedly named after the things they look like ("the camel", "the dolphin"), many of them were mined by gulag prisoners in the Urals. The diminutive "Mephisto" came from Kolyma in 1944, one of the arctic "death camps", which Solzhenitsyn's "The Gulag Archipelago" called: "the pole of cold and cruelty".
The central showcase in the second room contains the Russian Imperial Regalia. Europe's largest cut diamond, the "Orlov" (on the sceptre), was once the eye of a Hindu deity in a South Indian temple. It was stolen by a French deserter in 1750 and eventually bought by Count Orlov in Amsterdam as a present for Catherine the Great. In the next window, the "Shah" diamond is inscribed with the names of three Indian and then Persian shahs (including Jahan) who owned it. The shah gave it to Russia after a mob killed the playwright and diplomat, Alexander Griboyedov (whose portrait stands by it) in Tehran.
Beyond the Borovistkaya Tower, turn right through the Alexander Gardens, under the bridge, and then left towards the Okhotny Ryad shopping mall. The sculptor Zurab Tsereteli (who made the infamous Peter the Great statue) designed this subterranean palace, whose glitz and glamour is as fake as the imperial treasures are authentic. It might be a good place to get lunch, though, or even buy your own jewellery if you want.
The Vernadsky State Geological Museum, on the other side of Mokhovaya Ulitsa, was originally founded in 1755. It is open on Tuesdays, Thursdays and Saturdays 11 a.m. to 5 p.m., costs 80 roubles, and is packed with venerable lumps of fossil tree and smoky quartz. It is arranged thematically with historical collections, geological surveys and even a collection of "rocks that look like other things", a kind of "wunderkammer" full of hedgehog-shaped fossils and flower-like crystals. There is a little shop here too with reasonably-priced souvenirs. If you still have any money left after that, you could go round the corner for tea at the Ritz Carlton on Tverskaya.