When Nisargadatta uses the word consciousness, it is ciccaya, the reflection of consciousness, he is referring to. Balsekar paraphrases N’s intent: “Consciousness is with a form, a reflection of awareness against the surface of matter. One cannot think of consciousness apart from awareness; there cannot be a reflection of the sun without the sun. But there can be awareness without consciousness.”
Nikhilananda in a footnote to his translation of the Drg Drsya Viveka says “on account of the superimposition of ignorance a modification appears known as mind which, though insentient… appears as conscious on account of the association of Consciousness or Atman with it.”
Dayananda in his commentary to the same work says he doesn’t “use the word reflection of consciousness” but if one does, understand that “the consciousness obtaining in the mind is as good as consciousness."
Tejomayananda, in his commentary to Drg Drsya Viveka 6 uses the following analogy: “The ‘water’ of the mind in the ‘bucket’ of the body reflects the light of Consciousness. In this reflected light the entire world of objects is illumined, that is, all knowledge takes place in this reflected Consciousness."
footnotes (extended quotes)
The Conscious Self (चिदात्मा), though self-luminous, has no manifestation, because from the absolute standpoint there is no other object which can be manifested by Consciousness. But on account of the superimposition of ignorance a modification appears known as mind (अन्त:करण ) which, though insentient, (being the product of) appears as conscious on account of the association of Consciousness or Atman with it. The Atman appears as buddhi when associated with antaḥkaraṇa. The buddhi, on account of its association with Consciousness, appears to be endowed with agency, will, etc.
~Nikhilananda
Samāveśāt, buddhau bhānam explains everything. The word buddhau is used to point out the whole faculty of thinking. Cicchāyā aveśataḥ buddhau bhānam. In the buddhi there is bhānam, there is shine, it becomes conscious. I don’t use the word reflection of consciousness. If you use the word, understand in this way: sūkṣma-śarīra becomes conscious, means mind becomes conscious. The consciousness obtaining in the mind is as good as consciousness.
~Dayananda
A dark room, Impenetrable by the sun’s rays, is next to a veranda. On a particular day there is light seen within the room. Upon investigation it is found to be the light reflected from a bucket of water kept in the veranda, since sunlight did not directly illumine the room. The water by itself has no light. The sunlight reflected in the water of the bucket illumines the various objects in the room. The ‘water’ of the mind in the ‘bucket’ of the body reflects the light of Consciousness. In this reflected light the entire world of objects is illumined, that is, all knowledge takes place in this reflected Consciousness. Physical science states that pure light can never be seen and that it is only in the reflected light that all objects are seen. This reflection of Consciousness is the light of intelligence or the spark of life in man.
~Tejomayananda
One morning, when I had paid my respects to Maharaj and sat down, I found that there were only two other persons present. Maharaj suddenly said: What is the difference between ‘awareness’ and ‘consciousness’, if any? When something like this happens, one does not really know whether he expects an answer, or whether he is merely thinking aloud. One hesitates to answer for fear of breaking the flow of his thoughts. But then, he might also say: Why don’t you answer? Have you been wasting my time, listening to the talks all these days? This morning, however, he carried on without waiting for an answer.
He observed that awareness is of the Absolute, and, therefore, beyond the three Gunas (Gunatita); whereas consciousness is something fed by, and limited by, the food-body. When the food-body is destroyed, consciousness also disappears. Mind you, no one dies – the body, made of the five elements mingles with the elements when it is lifeless, and consciousness, which is subject to the three Gunas, becomes free of the Gunas. Awareness is the primordial original state, prior to the concept of space-time, needing no cause, no support. It simply is. However, the moment the concept of consciousness arises on this original state of unicity, the sense ‘I am’ arises, causing a condition of duality. Consciousness is with a form, a reflection of awareness against the surface of matter. One cannot think of consciousness apart from awareness; there cannot be a reflection of the sun without the sun. But there can be awareness without consciousness. In deep sleep, for instance, there is no consciousness (it is resting) but awareness is certainly there, because, on waking, one is aware of having slept; but only on waking.
~Ramesh Balsekar
an extra quote not in the text above:
The Self is of the nature of Existence-Consciousness. All objects are known to exist because of this alone. The objects, however, differ in their subtlety. Generally, subtlety is measured by its pervasiveness. The subtler an entity, the greater is its pervasiveness. Inert objects, including the body, pervade their own form. The mind's pervasiveness extends beyond objects. The mind, being subtler than the body which houses it, is part of the subtle body. The gross body manifests the Existence aspect of the Self only. The subtle body is capable of reflecting both the Existence and Consciousness aspects, thus appearing sentient. It is to be noted that Existence and Consciousness are not two separable aspects of the Self. Existence is Consciousness. Light and heat are the nature of fire. They are inseparable. Yet water can manifest only its heat, whereas wood can manifest both heat and light.
~Tejomayananda