How To Identify A Monarch Pressing

Ways to identify a Monarch pressing:

In the runouts of most Monarch pressings you will find a "delta" number (△). All of these numbers were etched. Some of the △'s had a line through them. You can tell the date when the record was mastered by looking up this number (not necessarily when it was pressed).

From the mid-50's to the late 70's the most obvious way was to look for a stamped Monarch Record logo (a circled "MR") in the runouts. Sometimes this was stamped backwards. Not every pressing during this time was given this stamp, however.

In the mid-70's, the stamped (MR) logo was replaced by and etched, often combined "MR."

Until the late 70's, all Monarch pressings had a 2.875" (73 mm) chamfered pressing ring. 

They upgraded their machines when they moved from Los Angeles to Sun Valley in 1978 and the pressing rings changed to double rings, a small center ring (33mm) and one larger outer ring (70mm). 

Some pressings, in addition to a "delta" number, have an etched "MN" or an "MW" in the runout. This may or may not be present with a stamped (MR). This is mostly present with RSO and Polydor albums.

On many A&M and A&M-affiliated pressings in the 70's there is a "delta" number along with an "M" and a number (Example: M1 or M-6) along with the matrix number. There may or may not be an etched "MR" or stamped "(MR)" present.

In the 70's and early 80's Monarch's A&M masterings were used for international markets. The country name for the mastering was usually included in the runout, along with the delta number. The stamped (MR) is not always present, but an "M" and a number (Example: M1 or M-6) is.

K-tel coded pressings with an "11" on the labels (and often in the runouts

Atlantic added an "MO" on the label matrix

It the late 70's, Polydor coded Monarch pressings with a "24" on the labels

In the early 80's, A&M added a "C" to Monarch pressings

Some Asylum/Elektra pressings added "MON" to the label of a Monarch Pressing

Some London/Decca pressings added an "M" to the label matrix