I received my B-602 black belt today.
As expected of Hirota, it's a beautifully crafted, even lustrous Obi.
The embroidery (I opted for silver thread) is perfect.
After seeing this belt I realise that my old belts, which I thought were 'silk', were, in fact, satin.
The silk has a completely different quality; elegant, yet more subdued.
It's slightly thinner than the B-503, making it less stiff, and seems to hold the knot easier as a result.
As per usual, the assistance and support from Hamid was exceptional.