The Grand Duchess of Luxembourg, Maria Teresa, in the Emerald Tiara
It's one of the most striking and difficult to wear tiaras in modern Europe but there's certainly no forgetting this one. Like it or loathe it, the Luxembourg Emerald tiara won't ever be missed. It's a bit of a favourite of Grand Duchess Maria Teresa and its green stone has some very green and very royal credentials. For this standout set of jewels was made of gems rattling around looking for a home. That's real royal recycling.
The tiara was made by Chaumet in Paris in 1926 and its design is very much of its time. It's sometimes known as the Art Deco tiara because all those diamonds and that great big emerald are set in that style and then some. It was made up of jewellery sent form Luxembourg to Paris with the express intention of creating a new tiara. There are hundreds of tiny diamonds studding the filigree design, all rising to a very 1920s point at the top - the height of this central part is around 2 inches.
Grand Duchess Charlotte of Luxembourg soon after the tiara was created
But the star of this show is the huge cabochon emerald at the very centre of the piece. May is all about emeralds and this emerald is all about and everywhere in this tiara.It is huge and while it's the only stone of that colour in the whole piece, it dominates it totally. Just below is a square cut diamond that would be impressive any day of the week by anybody's standards but it is dwarfed by the emerald that gives this piece its name.
The tiara was made for Prince Felix of Luxembourg to give to his wife, Grand Duchess Charlotte, who wore it many times during her long reign which would go on until 1964 when she abdicated. Her daughter-in-law, Grand Duchess Josephine Charlotte, wore it many times and it has become a real favourite of Maria Teresa who has taken it to weddings, state dinners and the Nobel gala in Sweden.
Grand Duchess Josephine-Charlotte of Luxembourg in the tiara
It's a real divider of opinion - its very 1920s design makes it hard to wear with modern clothes but its Art Deco lines are extremely beautiful. Whether you're a fan or not, there's no getting away from the fact that this is a tiara and then some
The Emeralds for May collection will build throughout the month - keep up to date with it here.