LONDON (Reuters) - An investment vehicle for “unique” digital products such as artworks said it will float in London, in the latest sign of the investment craze for so-called ‘non-fungible tokens’. NFT Investments, established by the co-founders of cryptocurrency firm Argo Blockchain, said on Thursday they intend to raise around 10 million pounds ($13.77 million) by floating on the niche Aquis Stock Exchange Global Market. The firm said this would value it at 25 million pounds. NFTs are a digital signature saved on blockchain ledgers that allow someone to verify the ownership and authenticity of items, with one artwork selling this month for nearly $70 million. Sceptics have questioned how unique a digital artwork can really be and warned NFTs could be another bubble waiting to burst. ($1 = 0.7265 pounds)