di·a·dem 
(dīə-dĕm′, -dəm)
(dīə-dĕm′, -dəm)n.
1. A crown worn as a sign of royalty.
2. Royal power or dignity.
tr.v. di·a·demed, di·a·dem·ing, di·a·dems
To adorn with or as if with a diadem.
[Middle English diademe, from Old French, from Latin diadēma, from Greek, band, from diadein, to bind around : dia-, dia- + dein, dē-, to bind.]
diadem1853 silver, pearl, and diamond diadem by Alexandre-Gabriel Lemonnier (1808-1884), owned by Empress Eugénie of France