Aquarius has two rules-the traditional and serious Saturn and the innovative, radical Uranus. The Saturn influence of Aquarius has indigo blue nuances, while the Uranus influence has more electric blue such. Both of these colors are associated with Divine wisdom and intuition, indigo blue brings more of the Saturnian wisdom-one of a deep serious thinker who has gained his wisdom by having passed life's vicissitudes while the electric blue thinker is intuitive and gets flashes of knowledge fully formed! But no matter which blue you will choose it will lead you to more serious, philosophical contemplation and the ability to see things from a 'higher' viewpoint rather than purely for satisfaction of the ego or one's material comfort. Hence dark blue colors will help develop more humanistic and High minded qualities. Indigo can also help you detach from an emotional state and look at the situation from a more peaceful and objective point.
If you have people who are very passionate, strongly opinionated and partial about situations, the introducing Indigo in their life, will help them cool down, detach and become less partial through the influences of reason an objectivity which dark blue colors infuse.
It is not by chance that the business world loves Indigo color, because it instills in others the feeling of impartiality, ojectivity and interests of for the Great Good(how truthful this is, is another matter)
You can nurture these Aquarius qualities of wisdom, sobriety and cool headedness through eating Dark Blue fruits like plums, aubergines, blueberries, etc. or by wearing dark blue clothes.
Putting Indigo decoration at home/office/living environment is another way of triggering its energy
Indigo is not suitable for entertainment areas due to it its more sedative and contemplative effect but for more 'quiet' places. Bedrooms or treatment rooms for example. People find indigo is helpful for studying so this colour could be used as part of the decor of a library or study.
One also needs to be careful not to overdo the Indigo colors in their life, because they can increase the sense of separatedness and depressive tendencies. If you are such a person, you are better off, introducing some warmer colors like yellows, reds and oranges which are ruled by the Fire signs.
Bringing electric blue into your life will increase the Uranus energy of Aquarius-which more erratic but also excitable and full of surprises! If your life is in a rut and you feel totally stuck, add some electric blue to your wardrobe, you will be surprised how you will suddenly start receiving flashes of revelations and Eureka moments. This color is highly stimulating for people of science, heavy mental work, or other fields which need fast creative resolutions, progressive thinking and intuitive realizations! It is not by chance that I have chosen this color for my website- it targets to stimulate and open up your mind, help you find new solutions to old problems and inspire some flashes of awareness about your life. This is the color of Astrology which is ruled by the planet Uranus--astrology is a tool for more objective and detached look at your self and life, which can help you overcome your psychological complexes and issues. Aquarius is the sign which rules psychological hang ups(Saturn) and learning how to detach our selves from these(Uranus). Electric blue has this progressive influence which helps jolt us out of stupor and makes us more aware of the endless possibilities which are around us.
It is recommended for Aquarius Ascendant, Sun or Moon people to wear Dark Blue stones(Lapis lazuli, Blue Sapphire etc) because it helps strengthen their health. But I recommend these stones for anyone who want to introduce the cool, level headed and progressive Aquarius energy in their life.
To sum up: Dark blue colors have cooling off effect, they bring deepness of thought, wisdom, objectivity and detachment, while electric blue will stimulate your ingenious and intuitive mind for finding new solutions and your progressive ideas.