Ruby On Rails +MongoDB. How to work with dates?

Question

MongoDB

The collection has entries with Timestamp
"timestamp" : ISODate("2014-06-10T00:00:00Z"),
coll.find(:timestamp=>"ISODate(\"2014-06-10T00:00:00Z\") doesn't return these records (works fine with
_id and other parameters) Tried different date formats but didn't get these records How can I do this? :00Z")}) works fine in the console.