India: A sweeper cleans the side of a road near a replica of the Eiffel Tower amid heavy fog in the early morning in the northern Indian city of Chandigarh January 18, 2010. (Photo by Ajay Verma/Reuters)

There is an endless bounty of eye-catching gemstones throughout the world and this spectacular boulder opal is one unique beauty that looks like a shimmering crystal encased in a tree fossil. Its opalescent sheen seeps through the cracks of the seemingly wooden rings in lustrous hues of emerald green and aqua blue. Like something out of a fairy tale, the triangular piece radiates through an organic pattern mimicking the growth rings of tree.

A woman wears a face mask in the part of the city near neighbourhoods known for burning coal for heating in Ulaanbaatar, Mongolia January 26, 2017. Not many people in Ulaanbaatar wear masks to protect themselves against pollution. (Photo by B. Rentsendorj/Reuters)

A walruses at Hagenbeck Zoo in Hamburg, Germany on July, 7, 2015. (Photo by Werner Struss/Startraks action)

Undated handout photo issued by Carhenge Glastobury of the Carhenge installation by artist Joe Rush, on the site of Glastonbury Festival at Worthy Farm in Somerset. Made of 24 vintage cars erected in the centre of the festival, the installation emulates the ancient stone structure at Stonehenge. Issue date: Tuesday, June 20, 2023. (Photo by Matt Cardy/PA Wire Press Association)

German car manufacturer BMW presents the “Vision Next 100” concept car during the 100th anniversary celebrations in Munich, Germany, Monday, March 7, 2016. (Photo by Matthias Schrader/AP Photo)

A hot air balloon floats past an almost full rising moon on a warm fall evening near Encinitas, California October 5, 2014. (Photo by Mike Blake/Reuters)

A single object, a single shape, a single colour,' is how Anish Kapoor summed up Leviathan, his response to the Monumenta challenge this year. Radically departing from Christian Boltanski’s busy collage-like approach in Personnes for Monumenta 2010, Kapoor has filled the 13,500 square metre space with a single cavernous entity which surges through the Grand Palais roof.