The following information is taken from several sources on the history of this "color mutation" in the Ringneck Dove.
The following was taken from an email (1/12/2000) written by Garrie Landry (who knows Mr. Thibodeaux) and is told to the best of his knowledge. This is on the "possible" origin of the "Ivory" color mutation here in the US.
"I believe that Dr. Miller and Dr. Hollander first gave credit of the mutations’ existence to Julius Thibodeaux of Louisiana sometime in the 60’s .... (G.Landry).
Julius (still living today) was a notable dove breeder during that time and he had firmly established the Ivory mutation in his flock of doves, and perhaps even recognized its uniqueness. I believe that Dr. Miller et. Al. Decided to simply give credit to Julius for the mutations existence, even with some certainty … they knew that Ivory Ringnecks had been in dove collections in the southwest Louisiana area for sometime. [Cajuns were often known to raise the Ringnecks as a meat bird and therefore most communities in Southwest & South Central Louisiana had a substantial number of dove breeders throughout the countryside.]
The Ivory dove seems to have arisen from within this group of breeders and simply remained in the area for a long time. Eventually it was Julius Thibodeaux who recognized the significance of the birds and called it to the attention of others.
Incidentally, the local breeders never referred to "Ivory" as such, they were simply called "WHITE RINGNECK DOVES", not to be confused with the more common "white doves" (which lacked any colored neck ring) and of course the other common variety, the "Blond" was simply called the Ringneck Dove.
The ivory mutant color presumably on the blond background was described by Taibel, 1966, in Italy in Atti della Societa Italina di Scienze Naturali e del Museo Civica di Milano Vol. 105 Fasc II: 158-174. We know of no importations. In tracing back to the origin of our stock, we find that the same phenotype turned up in Rayne, Louisiana. Julius Thidodeaux was described as an elderly chap who kept doves in one large pen. Thidodeaux was the source of ivory doves raised by Frank Webb in Port Arthur, Texas as well as by Ron Young of Huston. Webb was the source of ivory doves to Richard Burger of Newark, Delaware. Burger donated 4 ivory doves (one male and three females) to us 3 May 1971.
Taibel, 1969, also published on the dark ivory as I interpret it. Taibel called it pearl ash, and got it by crossing with another species, S. decipiens and reextracting it (Natura-Soc. It. Sc. Nat. Civ. St. Nat. e Acquario Civ., Milano 60/1:32-40 15-II.). The eyes are noticeably lighter than normal. Closer examination makes evident a rather finely mottled appearance of the iris, of the red to light or no pigment.
Juvenile ivory doves (as with rosy juveniles) closely resemble blonds. Their forehead feathers are distinctly lighter, and the tail bar centrally bleached, but less noticeable than in the adult.
Ivory plumage appears to have a dilution effect similar to blond. Ivory is less "brown", or is a bit more "gray", than a blond. The primaries (remiges) appear more dilute in ivory than in blond and have a more pronounced white tip to the primaries, which is barely detectable in the dark wild-type and slight in the blond. The primary coverts show a tiny stippling effect of dilute pigment versus almost no pigment as do the primaries themselves in the middle of the feather. This is especially noticeable in those primaries near the middle of the wing. The stippling is more marked on the leading edge of the feather. the secondaries appear quite free of the stippling.
The rectrices or main tail feathers have the tail "band" or pigmented area lightened centrally. The lightened area is not so much stippled as in the wings but more bleached, much as in recessive opal of pigeons. See Miller, 1976 Pigeon Science and Genetics Newsletter 2:24. Dr. W. F. Hollander and myself obtained a cross of such and opal pigeon with and ivory dove. The offspring was normal. Therefore, these mutants are non-allelic.
The breeding results or family data that I collected agrees with Taibel’s. My demonstration of recessive inheritance for ivory involved classifying 1,063 progeny of 8 kinds of matings, (table 2 in ADAN Nov-Dec ‘84). The ivory class is consistently deficient in numbers although accepatable for the statistical test of chi-square. But one type of mating (P=.027) was statistically, significantly different from expected. This may be explained by misclassification as hatchlings which died early preventing correction in the older squeaker. Or, perhaps, ivory homozygotes are detrimental during incubation. Or a combinatin of these is possible. Also chance might be involved. The reciprocal cross is as expected, and when combined yields a tolerable chi-square value (X2) of 3.42.
The motting of the eye can be called a pleiotrophic effect of the ivory gene. Genetically, pleiotrophy is the action of a single gene that results in more than one kind of detectable effect, often without obvious causal reasons. For example, blue eyed, white furred cats are usually deaf. The deafness has no obvious relation to the white fur or blue eyes, but one gene controls the total difference from normal cats. Similarly the ivory gene also controls mottling ofl the eye. Originally I thought ivory also controlled a very light color down (about white) on newly hatched squabs. I found that white down separated alone, which is not possible with pleiotrophic genes. Therefore, I am dubious that ivory always must have whitish down in the squab.
Interactions: Ivory on a blond background yields a blackish collared very light colored bird. The black half collar is diluted a bit more in blond-ivory birds than in ivory or blonds, but not noticeably so with a superficial glance. This light ivory also may be called show-ivory, since fanciers prefer it somewhat to the ivory on a dark background (the single mutant form). Ivory combined with rosy yields a "heavy cream" or light tan bird. If blond is included it is a light cream. Cream is a very attractive, even beautiful color, pied ivory is as most would expect. Perhaps we should leave fuller descriptions of interactions to a later section.
The following is from Prof. Bob Lockhart's book on the Ringneck Colors.
IVORY: This bird has an ivory to pearly body, head
and tail color; sometimes referred to as a dirty white. The "neck
ring" is dark gray to black. Eye color is "mottled".
Click on the
book link to find out about Prof. Lockhart's
book. 
An interesting note on this mutation: when Ivory is combined with another color & is visual the head, throat, chest and belly areas are white. Also mutants that are homozygous for Ivory will show the "mottled iris of "Ivory"; such as the Ivory Albino.
The Ivory mutation is "autosomal" = it is not sex-linked. It is a recessive mutant. For example breeding a visual Ivory (either sex) to a wild type (of the opposite sex) will produce wild type young of both sexes and all will carry the gene for "ivory" hidden. Breeding this "split young to the Ivory parent or another unrelated visual Ivory; or to similar birds with the Ivory gene hidden will give a percentage of Ivory offspring.
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