The kingpiece from Birka grave 523 has a damaged head, and the 20 pieces found are most likely not a complete set.
The reproduction of the kingpiece is approximately 19mm in diameter, in a light blue transparent glass trailed with black glass in a spiral. Each gaming piece also has a base diameter of approximately 19mm. As each piece is individually handmade they will vary slightly in diameter.
The photo below shows the kingpiece with a selection of gaming pieces, which are available individually. The gaming pieces are available in their own listing.