Cameos in raised relief of the Olympic gods. The seven gods depicted are the GODS OF THE PLANETS in correct order to their relationship to the seven days of the week. From left to right they are: Diana the moon for Monday, Mars for Tuesday, Mercury for Wednesday, Jupiter for Thursday, Venus for Friday, Saturn for Saturday, and Apollo for Sunday.   This was created in Italy in the mid 19th century.  It is made from Vesuvian lava or a soft stone, and gold.

Monday -- Moon's day Middle English monday or mone(n)day Old English mon(an)dæg "day of the moon" Latin dies lunae "day of the moon" Ancient Greek hemera selenes "day of the moon" In Roman mythology, Diana was the goddess of the hunt, the moon and birthing.	The crescent moon, sometimes worn as a diadem, is a major attribute of the goddess.
Tuesday -- Tiu's day Middle English tiwesday or tewesday Old English tiwesdæg "Tiw's (Tiu's) day" Latin dies Martis "day of Mars" Ancient Greek hemera Areos "day of Ares" In many languages, Tuesday is named for the planet Mars or the war-god, in Latin Martis Dies ("Mars' Day"), surviving in Romance languages as Martes (Spanish), Mardi (French), Martedi (Italian), Marţi (Romanian), and Dimarts (Catalan).
Wednesday -- Woden's day Middle English wodnesday, wednesday, or wednesdai Old English wodnesdæg "Woden's day" Latin dies Mercurii "day of Mercury" Ancient Greek hemera Hermu "day of Hermes" Woden is the chief Anglo-Saxon/Teutonic god. Woden is the leader of the Wild Hunt. Woden is from wod "violently insane" + -en "headship". He is identified with the Norse Odin. Mercury is the patron god of financial gain, commerce, eloquence (and thus poetry), messages/communication (including divination), travelers, boundaries, luck, trickery and thieves; he is also the guide of souls to the underworld.   Hermes is the Greek god of commerce, invention, cunning, and theft. He is the messenger and herald of the other gods. He serves as patron of travelers and rogues, and as the conductor of the dead to Hades.
Thursday -- Thor's day Middle English thur(e)sday Old English thursdæg Old Norse thorsdagr "Thor's day" Old English thunresdæg "thunder's day" Latin dies Jovis "day of Jupiter" Ancient Greek hemera Dios "day of Zeus". Thor is the Norse god of thunder. He is represented as riding a chariot drawn by goats and wielding the hammer Miölnir. He is the defender of the Aesir, destined to kill and be killed by the Midgard Serpent. Jupiter (Jove) is the supreme Roman god and patron of the Roman state. He is noted for creating thunder and lightning. Zeus is Greek god of the heavens and the supreme Greek god.	Emblems of his hammer, Mjölnir, were worn in defiance and Norse pagan personal names containing the name of the god bear witness to his popularity.
Friday -- Freya's day Middle English fridai Old English frigedæg "Freya's day" composed of Frige (genetive singular of Freo) + dæg "day" (most likely) or composed of Frig "Frigg" + dæg "day" (least likely) Germanic frije-dagaz "Freya's (or Frigg's) day" Latin dies Veneris "Venus's day" Ancient Greek hemera Aphrodites "day of Aphrodite" Freo is identical with freo, meaning free. It is from the Germanic frijaz meaning "beloved, belonging to the loved ones, not in bondage, free". Freya (Fria) is the Teutonic goddess of love, beauty, and fecundity (prolific procreation). She is identified with the Norse god Freya. She is leader of the Valkyries and one of the Vanir. She is confused in Germany with Frigg. Frigg (Frigga) is the Teutonic goddess of clouds, the sky, and conjugal (married) love. She is identified with Frigg, the Norse goddess of love and the heavens and the wife of Odin. She is one of the Aesir. She is confused in Germany with Freya. Venus is the Roman goddess of love and beauty. Aphrodite (Cytherea) is the Greek goddess of love and beauty.	Several plants were named after Freyja, such as Freyja's tears and Freyja's hair (Polygala vulgaris), but during the process of Christianization, the name of the goddess was replaced with that of the Virgin Mary.
Saturday -- Saturn's day Middle English saterday Old English sæter(nes)dæg "Saturn's day" Latin dies Saturni "day of Saturn" Ancient Greek hemera Khronu "day of Cronus" In December, he was celebrated at what is perhaps the most famous of the Roman festivals, the Saturnalia, a time of feasting, role reversals, free speech, gift-giving and revelry (Note:  called Christmas today). Saturn the planet and Saturday are both named after the god.
Sunday -- Sun's day Middle English sone(n)day or sun(nen)day Old English sunnandæg "day of the sun" Germanic sunnon-dagaz "day of the sun" Latin dies solis "day of the sun" Ancient Greek hemera heli(o)u, "day of the sun" Old English sunne, from Proto-Germanic *sunnon (cf. Old Norse, Old Saxon, Old High German sunna, Middle Dutch sonne, Dutch zon, German Sonne, Gothic sunno), from PIE *s(u)wen- (cf. Avestan xueng "sun," Old Irish fur-sunnud "lighting up"), alternative form of root *saewel- "to shine, sun" (see Sol). "the sun," mid-15c., from Latin sol "the sun," from PIE *s(e)wol-, from root *saewel- "to shine, the sun" (cf. Sanskrit suryah, Avestan hvar "sun, light, heavens;" Greek helios; Apollo:  Olympian deity, god of music, poetry, medicine, etc., later identified with Helios, the sun god; the name is a Latin form of Greek Apollon, said to be perhaps related to an obsolete Greek verb meaning "to drive away" Ra:  "hawk-headed sovereign sun god of Egyptian mythology," from Egyptian R' "sun, day."
Above information taken from and .