This may be an ideal case of "customer education." Ask your brother
why he wants the rings to be 24K and explain the down-side of that
choice (they will be soft and "mush" out of shape very easily, and
not handle "normal wear-and-tear" easily at all). Offer some
suggestions for alternatives that will help him meet his goals.
If he really likes the rich, dark look of gold, make the ring from
18K and depletion gild it or apply 24K keum boo on the surface... or
use a 24K bimetal. On the other hand, if it's the purity of the metal
that he likes, ask whether a different, more durable pure metal might
work for him. If he's insistent that 24K gold is what he wants, ask
him about whether you can do an inlay of it into steel or platinum or
some other contrasting metal... or even a different color of gold.
If you do end up making a 24K ring, I would recommend either fusing
it (not soldering it) or casting it. That will avoid the color
difference, melting point issues, and other possible problems of a
Hope this helps!
No Limitations Designs