In recent years, however, as the number of global rich has increased, so too has the size of the luxury goods market – stretching both upwards and downwards. For every Les Femmes d'Alger, there are thousands of designer handbags, exquisite pieces of jade, collections of rare stamps and vintage cars. So-called alternative investments have boomed over the past five years. In this period, the FTSE All-Share index of stocks increased by 31 per cent, but according to Knight Frank, the estate agency, the value of watches has increased by 49 per cent, art by 61 per cent, diamonds by 73 per cent and vintage cars by 140 per cent.