“I’ve got a few objects I want to put on display,” said Lord Rothschild.

For some of us, this might mean a dozen Dinky cars or ornamental spoons. Lord Rothschild was telling his project designer about a priceless collection of some 300 exquisitely crafted objects in precious and rare materials.

He wanted a room designed as a treasury in the style of 16th-century princes. And he’s happy to share it all with the rest of us.

The Rothschild Treasury opened this month on the top floor of Waddesdon Manor, which already houses a stunning collection of fine art owned by the family and cared for by the National Trust.

You need to climb a lot of stairs to reach it (no lift), but what a sight lies behind the stone archway and ironwork grille of this tiny barrel-vaulted room.

Almost all the items were collected by Baron Ferdinand de Rothschild who built the manor, his sister Miss Alice, James who inherited the manor, and Lord Rothschild who oversees the collection today. Some others are on loan from family members.

Display cases are packed with fascinating and unique precious items, some tiny and personal, some extraordinarily ornamental.

They range from a gold and diamond bracelet given to Miss Alice by Queen Victoria, an early astronomical clock, objects in exotic amber, jade and an amazingly carved nautilus shell, to a fine collection of wine silver reflecting the Rothschild association with Bordeaux vineyards.

Many of the family collected gold snuff boxes and there are some exquisite examples here, including one bearing pictures of Madame de Pompadour’s pet dogs.

Huge pearls, diamonds, emeralds and rubies decorate James’s mother’s eye-popping tiara and jewellery.

Other family passions are represented by archaeological finds sponsored by James’s father Edmund. Some objects bear Nazi inventory numbers after their wartime confiscation from the Paris branch of the family.

Every small shiny object has a story.

In a new venture for Waddesdon, smartphone users will soon be able to find out more via a free app, Smartify, which gives access to museum and art gallery collections worldwide. There is also a print guide available in the room.

The Rothschild Treasury is open during house opening times, at no extra charge.

See waddesdon.org.uk.