Why is Suigintou's title "Mercury Lamp?" Looking on the Rozen Maiden Wikia for the Rozen Maidens, I notice they all have titles


Suigintou = Mercury Lamp 
Shinku = Pure Ruby
Hinaichigo = Small Berry
Suiseiseki = Jade Stone
Souseiseki = Lapislazuli Stone
Barasuishou = Rose Crystal
Kirakishou = Snow Crystal
Kanaria = Canary Bird


i get most of them are either a trait they have (Hinaichigo is small, Barasuishou attacks with crystals) or their primary color scheme (Kirakishou is white like snow, Kanaria is yellow like the general depiction of a canary).

But I don't understand why Suigintou has the title of Mercury Lamp. From my understanding, Suigintou's color scheme is black (2013 anime) or purple (2004 anime) while Mercury as the metal is silver, while I don't think the planet is black or purple. Nor do I get how Lamp fits.

So how does Suigintou's title match with her?
I think it refers to the metal mercury (水銀)　which is silver as Suigintou's hair. 

It is fragile, it breaks easily (think of thermometer) and when it breaks it is very poisonous. Just like her. She's not bad, just a bit unfortunate and later became evil and poisonous.

It's hard to guess why the kanji for lamp is there though, but during the victorian era, there were lamps with mercury glass reflectors, so it would emit more light