Unidentified H Maker Mark On Arts & Crafts Pin

[Abbott]

Sterling, turquoise and diamond Arts & Crafts style pin, seemingly American. I have been unable to identify the mark.

[Aguest]

:::: The diamonds seem like older mine-cut diamonds, the turquoise seems like older Persian turquoise, a picture of the pin mechanism would help to better understand the piece, and I'm not sure what stone is in the teardrop-dangle part of the brooch (is that a black stone?). :::::

::::: The initials are DLH or LDH or PLH or LPH but it really seems like the letter "H" is the last name of the artist. :::::: The sterling silver seems "cast" so the casting process seems to have made the initials slightly debatable. ::::::

::::: I'm still trying, maybe the Jewelry Forum would attract more experts in this area, is the center stone an opal? :::::

[Aguest]

:::: I keep encountering "DLH DEPOSE" necklaces, so if "DEPOSE" means "copyrighted" does anyone know who the "DLH DEPOSE" hallmark corresponds to? :::::: The "DLH" hallmark on this sterling silver necklace might be related to the "DLH DEPOSE" pieces ::::::::