There are several examples here firms have used block chain in supply chain.
>>>>Diamond-giant De Beers uses blockchain technology to track stones from the point they are minded right up to the point when they are sold to consumers. This ensures the company avoids ‘conflict’ or ‘blood diamonds’ and assures the consumers that they are buying the genuine article.
>>>>>>There are several supply chain startups such as Cloud Logistics who saw an opportunity to provide blockchain-enabled supply chain solutions to improve efficiencies and reduce costs for the massive supply chain industry.
I've currently been reviewing Blockchain use-cases in Supply Chain, and have found Blockchain Technology a great opportunity to make Supply Chain Networks more cooperative, by solve problems of information, cash, and inventory flows. It can eliminate the role of Customs, and increase international supply chains' efficiency. Indeed, there are more advantages discussed in the literature. As mentioned by Faisal Khalil, "there are many startups" developing in the world, and you can follow giant investments such as IBM (Mohamed Azab), and etc.
I recommend you to take a look at Dr. Erik Hofmann's book "Supply Chain Finance and Blockchain Technology The Case of Reverse Securitisation". Though, In my personal opinion, Blockchain's mission is to make the world a more trustworthy and fair place to live. Therefore, it interests me to use the technology in a way that helps supply chain members trust each other, and gain more fairly.