Partly the origin of the edge in tetraploids is the result of the tetraploid conversion process. Whether this is the result of the doubling of the chromosomes or a mutation that consistently occurs as a result of using colchicine I am not sure. I suspect the former but I have no evidence to support this other than my own anecdotal observations. Tet SILOAM VIRGINIA HENSON and Tet BARBARA MITCHELL have gold wire edges while the diploids do not. These edges once present appear to be recessive.
The effect however can be intensified by the accumulation of these recessive alleles. Wire gold edge crossed to wire gold edge yields mostly offspring with wire gold edge or no gold edge. In a small proportion of cases the effect is greatly elaborated e.g. WEDDING BAND (Stamile, 1987) (wire edge) X (PINK SCINTILLATION (Stamile, 1984) x induced seedling)( wire edge) yields ADMIRALS BRAID (Stamile, 1990)(elaborate edge). The origin of the edge in ADMIRALS BRAID is not simply WEDDING BAND; it is the cumulative effect of both parents. In the same way the origin of the edge in WEDDING BAND is both PORCELAIN PLEASURE (Stamile, 1983) and FRENCH FROSTING (Munson, 1978). These are not the only sources of the origins of gold edges in Tets. Bill Munson's lavenders going back to RUFFLES ELEGANTE (1980); Harold Harris's conversion of HOPE DIAMOND (MacMillan, 1968) leading to PEARLS AND GOLD (Harris-Benz, 1987); and my own EVER SO RUFFLED (1983) which many don't realize is a gold edge on a gold flower.