The sale of the world’s most expensive postage stamp will test the value of shared ownership. London-listed philatelic specialist Stanley Gibbons (SGI.L) on Tuesday paid $8.3 million for a British Guiana One-Cent Magenta stamp, issued in 1856. The company, which has a market value of just $19 million, wants to make the stamp more accessible by selling fractional shares, allowing owners to admire it digitally and profit from future increases in its value. It’s an admirable attempt to cash in on the vogue for digital assets. But Stanley Gibbons faces a hard sell. The sale price at a Sotheby’s auction was below the $9.5 million the stamp fetched in 2014. It’s one of the few rare assets that has not soared in value in recent years – prices of luxury collectables on average doubled in the past decade, according to Knight Frank. Stanley Gibbons is funding its purchase through a five-year interest-free loan from its majority shareholder. Stamp collectors are enthusiasts for specimens with errors. This could also be a mistake. (By Karen Kwok) On Twitter http://twitter.com/breakingviews Capital Calls - More concise insights on global finance: BBVA layoffs are just the start for Europe’s bank read more Ferrari picks new driver for tech era read more Chinese producer price pop pains policymakers read more Chinese jeweller peddles gems of diversification read more FBI phone hack is a VC dream come true read more