Bolt duplication glitch
The bolt duplication glitch was leaked to the wider public on 22 February 2010. This glitch was patched without a system update on 23 February. It enabled players to gain tens of millions of gp per hour by significantly multiplying the amount of dragon bolts during enchanting.
The player used a chisel with a cut gem. When the option was given to cut the gem into bolt tips, the player opened up their mage book and then clicked make-all on the gem. As soon as the player started making bolt tips they clicked enchant bolts on the dragon bolts. The first 10 bolts would be enchanted, and then every 1 bolt after that turned into 12 enchanted bolts.
The glitch could be used to multiply any bolts, but due to the scarcity and value of dragonstone, combined with their frequent use in PvP, dragon bolts were the most widespread kind of bolts that were used while exploiting the glitch.
Jagex made an official statement about this bug on 2 March 2010, in which they said that they banned several high-levelled players, including one with a Total level of 2376 (The highest Level achievable at the time) and one with over 1000 days of total playtime. Several fan-site forums reported an increase in ban-risk for all types of offences in the days following the glitch; therefore, it seems Jagex temporarily increased its watchfulness in order to seek out those players who did participate in the glitch.