Diamond Blockchain Initiative

While not completely familiar with the technology that DeBeer's is using, I can comment on the general advantages of blockchain for Chain-of-custody.

I am more familiar with pharmaceutical and food safety applications and so will comment on those.

Firstly, with chain-of-custody one is tracking something external to the blockchain, so there is no getting around the fact that one needs to place some trust in the entities writing to the blockchain.

The better way to think about it is that the blockchain allows you to trust "who" wrote to it and "what" they wrote, not whether what they wrote was an accurate reflection of the real world or not. (The real-virtual mapping problem)

In the pharma industry for example you have hundreds of manufacturers and thousands of wholesalers and tens of thousands of pharmacies, thousands of carriers, thousands of re-packers, thousands of customs brokers, hundreds of freight forwarders and 3PLs etc.

Furthermore, unlike Diamonds, it is not a simple linear flow of serialized items. Many items are actually lot-tracked and not serial-tracked. So, now you have the notion of splitting of lots and blending and combining of lots. Additionally items will go back and forth between distributors.

Additionally, you have IOT readings along the entire provenance history like temperature, humidity, location etc.

When an entity receives a serial or lot tracked item they can trace its provenance on the blockchain and decide whether and to what degree they want to trust whether what the previous entities wrote to the blockchain needed to be second guessed.

Often when receiving, entities will perform some sort of QA. The degree of QA will be dictated by who, what, when and where the item went through in its entire journey.

If they have high trust in the entities in the chain of custody they may only do partial check (eg. check for no broken seals), but if they don't trust the entities in the chain they may do a full assay of a sample or they may take the middle ground and do a quick spectrophotometry analysis. With any of these results they can write their certification to the blockchain so that subsequent entities may not have to re-certify if they trust this intermediate entity.

So, one way to think about this is that chain-of-custody is not all or nothing, but rather based on degrees of trust. Also every participant views the situation differently based on whom they trust.

Now back to the original question of whether this could be done with a central database instead of blockchain. The answer is "of course", but now even the who and the what is potentially suspect IN ADDITION to the virtual-physical mapping problem.

Blockchain-based chain-of-custody solutions allows one to design a system focused only on mitigating the real-virtual mapping problem.

Yes, you are right. But if you imagine the full provenance of a lot or serial tracked item having hundreds of "messages", it is true they could all be digitally signed by the entities submitting them which would prove "who" sent the "messages".

However, keep in mind that all these messages need to be correlated and subject to business logic and validations. For example, the business logic might dictate that one cannot record a temperature reading to the blockchain if the chain-of-custody does not show you as the current possessor of the item.

Alternatively, the business logic may say that you cannot blend a non-blendable lot.

There are thousands of business rules that need to be enforced along the way.

With the (say) PGP approach, you would need to ADDITIONALLY trust that the entity applied these business rules correctly. Also in this approach, there is no single version of the truth. So, every entity maintains its own version of the truth leading to huge synchronization problems in addition to trust problems.

So let's say we etch a QR code into each diamond which is only visible with a microscope. This is not unfeasible. In fact "Polar Bear" diamonds carried an etching of a polar bear. [1]

So once you have the etching of a QR code then it makes sense for a blockchain, because then it makes determining the provenance for a diamond easier. And you could track stolen diamonds much, much easier.

Though, I would be disappointed if DeBeer's only allowed it for their diamonds only.

[1] https://www.theglobeandmail.com/news/national/diamonds-mined...

Authentication of a write operation is not the only problem a blockchain system solves. Using a public blockchain, for example, you are assured that: 0) all writes are authenticated 1) all the data written will be accessible to anyone Now contrast it with a centralized solution where admit can just restrict access to some data. Yes, all writes are authenticated, but who cares if you cant access them? 2) The history of all writes is also reliably preserved and accessible to anyone. 3) In case of smart contracts, the business logic is visible to you upfront. You can study the contract and decide if it is fair to participate. You can study the history of that contract also. 4) All "redundant" nodes have proper incentive to participate in the activity. They gain value just by validating and processing your transactions.

My point is that this is just not achievable using traditional DBMS: the original premises ("trust model" and incentive model) of those systems are very different.

Please correct me if I am wrong somewhere.