Returning highest value for multiple unique ID's

Hi there,

I'm working through drill hole data with linked down hole assays. There are over 500 drill holes, and each hole can be down to 250 m depth. Every metre has an associated sample and gold grade attributed to it, meaning there are many thousands of rows of data. 

I'm trying to find a formula filter shortcut for returning only the highest grade sample for each unique hole ID, ignoring all lower grade samples. Can anyone help me with this?

Cheers!