An impressive 50.35 carats fancy intense yellow briolette-cut diamond pendant necklace. Estimate €1,450,000 – CHF1,900,000 ($1,460,584 - $1,913,869). Photo Christie's Image Ltd 2015

The fancy intense yellow briolette-cut diamond, weighing approximately 50.35 carats, to the diamond-set cap and box-link gold chain, 50.0 cm, mounted in gold

Accompanied by report no. 122099101 dated 2 April 2003 from the GIA Gemological Institute of America stating that the diamond is Fancy Intense Yellow colour, SI1 clarity.
Please note that the report is more than 5 years old and might require an update. 

Christie's. GENEVA MAGNIFICENT JEWELS, 10 November 2015, Geneva