"In the language of the alchemists, matter suffers until the nigredo disappears, when the 'dawn' (aurora) will be announced... and a new day will break." Carl G. Jung
The word "albedo" signifies dawn, "alba." In transformational tarot the albedo usually signifies a breakthrough through the dark and into the light, like an idea that suddenly comes up and resolves a quandary, or when something makes sense out of the blue, bringing clarity and hope and even resolution to a given situation. I see albedo as a form of coagulatio, and perhaps this is the way that the reader could make the basic distinction in alchemy between coagulatio and coniunctio.
Coniunctio brings up the idea of a marriage or reconciliation of opposites; it is usually linked to the Hermetic Law of Polarity. Out of this marriage of opposites something new comes forth. When we are talking about personal transmutation, in modern times we compare coniunctio to the ability to join the shadow with the self, into a new person, like in the process of individuation.
Coagulatio might suggest more the ability to jell, crystallize or congeal what was not solid before, or what was dispersed and in apparent disarray; a process that brings congruence and solidity to what previously appeared diffused, incoherent, incongruent. We know when we are experiencing a period of being unable to understand something, and we go back and forth in our mind, considering, contrasting, rejecting ideas, imagining new scenarios. Until suddenly, it just happens. Something comes forth that helps us see the light at the end of the tunnel, the ability to understand what seemed previously incomprehensible, as if a veil or blindfold is pulled from our eyes.
This is all part of Gnosis, when obscurity is replaced by light, and the alchemical gold or the Philosopher's Stone is made available to us, even if fleetingly.
The card above is from the Vision Quest Tarot and is called "Insight." It reminds us of a breaking dawn, or a sign of relief after darkness, stagnation, or oppression. Below you find two versions of Key 19, The Sun, which can also signal an alchemical state of albedo.
All these images could easily apply to a situation in a card reading symbolizing some form of coagulatio. This could represent to us the Philosopher's Stone, the ability to reach a higher level of consciousness
Illustrations: Vision Quest 8 of Fire Key 19, the Sun from BOTA deck; PCSmith deck, 1910.