A Brief History

Wax seals have been used in letter writing for centuries. Originally reserved for use by the wealthy and ruling classes (especially bishops, monarchs, royalty, etc), these small pieces of wax are not just decorative adornments to secure a beautifully written letter. They have been used throughout history as a signature; to legitimise formal documents, to prevent forgeries,  and in authenticating papers regarding laws and decrees (e.g.  historical ‘privy seals’ or ‘Great Seals’ of Monarchs). 

They have also been used to preserve the confidentiality of important documents with a tamper proof seal (traditionally, the wax used became brittle once it hardened, meaning that the letter could not be unfolded without damaging the seal) although it is important to note that in earlier times where reading comprehension was low among the public at large, the role of the seal was more for the authentication than security.  

Then, with colonization and increased emigration as time went on, and upon the advent of 'Great Age of Letter Writing' in the 18th century, the tradition eventually became part of the ritual of personal writing; to friends and family with news from home or away. Essentially, they are a signature of the bearer.

Selecting a seal design

Traditional seals would be unique to their owner. Think family crests, initials. For high-ranking or important figures of times gone, a custom made signet ring with their unique seal would be worn. Signet ring seals have historically been viewed as symbols of incredible power, as they attest to the authority of the bearer and only one was valid at a time, e.g. the 'great seal' of the King or Queen. Upon their death, the signet ring would be destroyed and a new one commissioned for their successor. 

Family Crest
Used in official family correspondence, regarding family or letters to and from other family members. A full Coat of Arms is not usually used for a seal - it should be the crest only. May also feature a latin motto printed around the outside.

Monogram
Used in both formal and informal letters, and naturally would only be used by you. Usually features 1-3 initials. Script or serif fonts acceptable.

Motto / Graphic
These are more novelty, and wouldn’t be used for formal correspondence, or letters to someone that you aren’t familiar with. Use between friends. See our Selene Wax Seal Series for reference.

Selecting the colour

	Red A common seal colour, wax reddened with vermillion (cinnabar) pigment was among the first of the coloured seals used. For this reason if you research further into the history of wax seals, red is the colour you'll see for most of the preserved examples of historical wax seals. This is your ‘default’ wax seal colour, used for all formal correspondence but it is also fine to use for informal notes if desired. However you would NOT use red for letters such as condolences or to those in mourning - this would be seen as very bad taste.
	Blue A colour of romance and passion. In the 1880’s, there were five ‘grades’ of blue, indicating the strength of passion. The deeper the blue, the deeper the feelings.
	Green A colour of friendship. Use for informal correspondence.
	Black (and sometimes dark violet) A colour of melancholy. As a colour of mourning in Europe and North America, Black is reserved for important correspondence such as notifying a family member of a death, or sending your condolences. The colour Black will act as a signal to your recipient that the letter contains news that they may need to prepare themselves for. For this reason, you wouldn’t use Black for any other type of letter.
	White A colour of invitation. Expect to see this seal on wedding invitations and other more formal invites.
	Pink A colour of praise. Would be used with any letter of congratulations. May also be used by girls writing to friends.
	Metallic Such as gold and silver. These waxes are typically coloured using mica powders. Only correspondence between ‘lady friends’ would bear a metallic seal; these colours would be deemed far too ‘garish’ for gentlemen.

Mixed colours
Contemporary use of mixed colours is usually an aesthetic choice - but mixed colours can also convey multiple emotions and feelings. For example, say you are sending a letter of congratulations to a romantic partner; you may choose to mix pink and blue wax.

Obviously, the majority of these guidelines are rooted in a history with weight always put in cisgender roles and class hierarchy. They are not necessarily what we would view as acceptable today. Go forth and joyfully use your wax seals in all colours and styles, adding them to everything you having lovingly created with a flourish!

Sources:
teknikaldomain.me
victorianpassage.com
fredlake.com
stampsdirect.co.uk
archive.org