Terraria Text Color
In terraria, announcement-box-syntax can be used to display text in different colors. This post records some color codes of my common use. They may not be accurate since they are obtained using the colorpicker.
Announcement Box Syntax
To specify a color, use [c/<color code>:<text>].
For example, [c/FFFF00:114514!] will be displayed as
114514!
To display an item, use [i/<attribute>:<ID>], where <ID> is the item id and <attrbute> can be in the following syntax:
s<number>,<number>is the stack number.p<id>,<id>is an id of modifier.
There are also syntax displaying player names, achievements and controller buttons.
Rarity color
Grey: #787878
Blue: #8F8FFF
Green: #96FF96
Orange: #F7C291
Light Red: #FF9696
Pink: #FD95FD
Event color
#32FF82: The Blood Moon is rising...
#AF4BFF: The old one's army is approaching!
#E11919: Player was slain...
#FF1919: NPC was slain...
#FF00A0: Looks like xxx is throwing a party
#327DFF: NPC has arrived!
#FFF014: Spawn point set!
References
Status messages - Official Terraria Wiki