Kingdom of Jerusalem could feel the noose being put around it by Saladin, the Ayyubid Atabeg of Egypt. 
As a form of economic warfare Crusader mints in both Tripoli and Acre would strike imitations of Fatimid & other Islamic gold coins using debased gold. The hope was that merchants would see these imitations that are lower quality gold & decide to accept all Islamic gold Dinars at a lower value. 
How effective was this is hard to say, but the imitations used a barely legible form of Arabic writing. It turns out that having a Frankish Crusader who knows nothing about the Arabic alphabet cut the die does not make for a convincing counterfeit. 😂