The Ruby Group of two 600 ton Fourth Rate vessels were part of the 1651 Programme.

The size of these vessels grew from the 1647 predecessors with 600 tonners being much broader.

The two 600-ton vessels would be completed as 42-gun Fourth Rates.

[1] The construction one vessels was assigned to Portsmouth Dockyard with one vessel contracted to Peter Pett I of Ratcliffe.

The dimensional data was so varied that it will be listed on the individual vessels along with their gun armament composition.