Over the weekend the value of the digital currency hit more than $100bn (£74bn) according to some market monitors.

This valuation is higher than the other popular crypto-cash system - Ethereum.

Each Ripple coin, called an XRP, is now worth about $2.34 - far higher than the half a US cent they were worth a year ago.

Bitcoin still remains the most valuable crypto-currency. The value of the 16.8 million bitcoins in circulation is now worth a nominal $231bn. Each bitcoin has a value of about $13,580.

Bank payment

Ripple has sought to establish itself as a safe alternative to other crypto-currencies by emphasising its links to existing financial institutions.

Ripple was set up to help banks speed up and modernise how they pay each other. So far, about 100 banks have signed up to use its payments system. Bank of America and UBS are among its customers.

Analysis - Rory Cellan-Jones

"Forget Bitcoin, that's old hat - it's time to get into Ethereum, Litecoin and Ripple."

So goes the message from the crypto-currency enthusiasts when critics mention Bitcoin's failings as a currency and its profligate use of energy in the mining process.

They also like to use a dubious measure - market capitalisation - to show just how significant a force a crypto-currency like Ripple, or rather its crypto-currency XRP, has become.

When investors talk of the "market cap" of a company such as Apple - about $870bn right now - they reach the figure by multiplying the number of shares by their price to calculate the value of the business.

That price can move around pretty sharply but you will have little trouble selling your shares and turning them into hard cash.

Ripple's market cap has been calculated by multiplying the number of XRP coins in existence by the current dollar exchange rate.

But unlike Apple, Ripple has no reliable assets or revenue streams backing up that rate, and changing it into "fiat currency" - that dreary old concept that is supposedly heading for extinction - may prove tricky if everyone heads for the exit at once.

So as with everything connected with crypto-currencies it's best to take their market caps with a sackload of salt.

Growing adoption of Ripple seems to have driven its rise in value.

Over the weekend, three of Japan's big credit card companies revealed they had signed up to use it to handle payments and settlement.

Prior to this announcement, some South Korean and Japanese banks announced a pilot project that would use Ripple to handle cross-border payments.

Both events are believed to have prompted the bump in value.

Unlike other crypto-currencies, Ripple coins or tokens are not mined by the members of the network that processes transactions. Instead, the coins have been pre-mined and are slowly being released as the network is used.

Eddy Travia, head of crypto-cash financier Coinsilium, told the Financial Times that the higher value could be a problem for Ripple which had done well to win banks over to its technology.

"The worry is that when the price goes up so much it moves the focus from the technology to just the speculation," he told the paper.