There are a number of ways in which authorities estimate the dates when pottery vessels were made.  Some use museum collection data for items that are similar to that being investigated and others use the literature published in the 20^th century for clues, as that was a century of significant contributions to published data.  There are known dates for when slips changed, when glazes were used and abandoned, and when vessel shapes changed.

According to information published by Harlow and Lanmon (see reference), Zia potters began experimenting with a new overall slip in the early 1920s—one that is an orange-tan color.  The authors arrived at that date based on the fact that collections made for the American Museum of Natural History in the 1910 decade contained no specimens of orange-tan slip pottery.  A second item of identification—that wiped on dark red band under the design area—was apparent on most of the orange-tan slip jars examined, and that red band disappeared around 1930, so that pretty well ties down the 1920s decade as the main one for use of the orange-tan slip.  The featured decoration provided by the artist is the capped feathers under and over the double rainbows.  The major ones are orange outlined in black and the minor ones are totally black. The orange rainbows are each outlined in black. 

Condition:  There was a vertical crack starting at mid-body going down to the bottom of the jar that has now been professionally stabilized and slightly over-painted.  Otherwise, there is no other damage or repair.