Introduced in 1910. Discontinued in 1917. I have never seen this back design, apart from the image in Mrs. Robinson's booklet and the occasional sample card in a salesman's sample folder or book. Very, very rare. The color in the red example above is generic.

The image for the blue card, above, is from a salesman's sample card that sold on eBay for $225 on February 22, 2017, pictured below. This may be the closest any of us get to a Margin Snowflake card.

  37. Lotus                                         39. Margin Star No. 1  


Note the hyphen in the name...