From Longman Business Dictionary
appreciateap·pre·ci·ate /əˈpriːʃieɪt/ verb [intransitiveI]1to increase in valueTheir art collection has appreciated substantially, almost doubling in value.
2FINANCE when a currency appreciates, it increases in value compared to other currenciesappreciate againstThe Egyptian pound has appreciated against other currencies, and this is not good for Egyptian exporters.