Bakumatsu Blue

While researching ceramics of the Edo Bakumatsu period (roughly 1853-1867) I noticed a blue color combination (medium gray/blue with a darker, but not cobalt blue, often  with (墨弾) Sumihajiki, a resist method used to on ceramics to leave white areas when painted or glazed.  I will call this "Bakumatsu Blue". Not all ceramics made during the Bakumatsu period used this blue combo, but it was widespread.  Similar combinations were used much earlier in the Edo period with slight variations.