This article mentions a value of $23M for lengthy crafting processes, which called in artisans from the UK and India to Singapore, Germany, and Sri Lanka and took over a year to produce.

To read the complete article, see:
A Coin Drenched in Over 6,000 Diamonds Pays Tribute to Queen Elizabeth II(https://www.naturaldiamonds.com/rare/a-coin-drenched-in-over-6000-diamonds-pays-tribute-to-queen-elizabeth-ii/)

This article said the coin was worth 18M Pounds.

To read the complete article, see:
COSTLY COIN Incredible rare coin worth £18MILLION with 4kg of gold and more than 6,000 diamonds is unveiled in honour of the Queen(https://www.thesun.co.uk/money/23868379/commemorative-queen-coin-east-india-company/)

Two years later this SPINK post asks 5.8M Pounds.

To read the complete article, see:
THE CROWN COIN(https://campaigns.spink.com/t/i-e-fiudjdy-ijtllkukji-h/)

Where have all the high-end collectors gone?

To read the earlier E-Sylum article, see:
'THE CROWN' GIANT COIN FOR ELIZABETH II(https://www.coinbooks.org/v26/esylum_v26n37a29.html)