Others were far savvier, and the fabulous collections that were part of the treasuries of Patiala and Mysore and Jaipur disappeared in the period between the merger of the states and the abolition of the privy purse in 1971. Most of the jewellery worn by members of the princely families have never since been seen again, though a few occasionally pop up at auctions.

And one such piece of jewellery is a two-strand, 68-perfectly formed natural pearls necklace that was part of a larger, seven-strand necklace last seen around the neck of Maharani Sita Devi of Baroda in 1948.

To be auctioned by Christie's on April 25 in New York, the necklace is considered the finest and rarest to ever come up for auction, and is expected to raise $7-9 million.

The house of Baroda was a major collector of jewellery, and Maharaja Khande Rao, in the 1860s, boasted of some of the finest, including a seven-strand diamond necklace that was rumoured to have some diamonds that once belonged to Napoleon Bonaparte, the pearl necklace, a "Hindou" necklace, as well as a pearl carpet that was studded with pearls and precious stones and evaluated, in 1865, at Rs 6 million.

In 1943, when Maharaja Sir Pratap Singh Gaikwad married his second wife, Sita Devi, it coincided with the royal family shifting their base and many of Baroda's treasures to their mansion in Monte Carlo.

Later, Sita Devi (popularly known as India's Mrs Wallace Simpson) divorced Gaikwad, keeping the fabulous wealth of the house of Baroda as her trophy, including the pearl carpet.

Those treasures have never been seen since, though the pearl necklace was brought back by the maharaja when he was ordered to return to India by the government for alleged anti-India activities.

The April auction of the pearl necklace consists of the most perfect pearls from the fourth, fifth, sixth and seventh strands of the original necklace set in a Cartier clasp and accompanied with a pair of earrings, a brooch and a ring.

As for where the carpet, the diamonds (that included the 129 carat "Star of the South" and the 78.53 carat "English Dresden") or the remaining pearls are, that's anybody guess - till they come up at the next auction.