the kimberley process would be nice, if it would work there is no impartial monitoring, so if you want that certificate for your conflict diamond, one corrupt participant of the kimberley process will be enough to ensure that you get the right paperwork.

human rights organisations say that the kimberley process would be nice if it would be implemented in such a way that it would actually work, but that it doesnt work due to lack of oversight. and the diamond industry says the kimberley process works, and doesnt offer any better alternatives.

also, the kimberley process is only targeted at conflict diamonds, that is, diamonds being used to buy weapons and/or fund terrorists or rebel groups. there is no system in place that would guarantee humane working conditions or safety of workers or prevention of child labor.

In order for a country to be a participant, it must ensure that any diamond originating from the country does not finance a rebel group or other entity seeking to overthrow a UN-recognized government, that every diamond export be accompanied by a Kimberley Process certificate and that no diamond is imported from, or exported to, a non-member of the scheme.
thats all there is to it. there may be modern-day slavery going on in the mines, as long as the mine is not being run by rebels, the diamonds will get their kimberley process certificates.

now if the kimberley process does not target poor working conditions and is not really effective in preventing conflict diamonds from entering the market, but when jewelers like to refer to it as an argument that the diamonds come from ethically sound sources, then the whole kimberley process is in fact only serving the purpose of a marketing tool.