You can earn diamonds without spending a shilling, and you can redeem them for real goods. What you cannot do is use them to pay a Knomart fee. That is deliberate, and the reasoning is worth setting out.
The rule
The $5 skills exam attempt and the $100 agent track are both cash only. So is the membership contribution. Diamonds redeem for goods at participating merchants and nowhere else.
What would happen otherwise
Skills badges carry the largest single weight in Profile Strength after merchant ratings. If diamonds could buy exam attempts, and diamonds come mostly from quiz answers, then ranking would become something you could grind your way into by answering quiz questions.
A merchant choosing between applicants would be reading a ranking that reflected quiz volume rather than verified ability. The badge would stop meaning anything.
The uncomfortable part, stated
This rule has a real cost, and it falls on the member with the least. Badges weigh heavily and cost cash, which means ranking is partly a function of being able to find $5. That is a genuine tension in the model, not something to wave away.
The bridge is the cash micro-task: community micro-tasks pay diamonds and Profile Strength, and higher-value ones pay cash. For a member with no money at all, that is the route to a first exam fee — and it is the load-bearing step in the whole on-ramp.
Why membership too
Membership funds the organisation. Diamonds are a reward the organisation issues. Letting one pay the other would mean issuing rewards to collect revenue from them, which is circular rather than sustainable.
What diamonds are for
Goods, at shops in your community. That keeps the value local, gives participating merchants footfall, and keeps the reward separate from the things that determine who gets work.
