Swami Hariharananda Giri in Karar Ashram 

For twenty years, I heard Baba Hariharananda say “Nirvikalpa Samadhi" is the Certificate once needs, to be able to say one is a "Master of Kriya Yoga".

This means one can enter and exit at will, the "pulselessness-breathlessness state" of Nirvikalpa-Samadhi, thru the techniques of Kriya Yoga.

This is the one advanced quality that all the masters of the Kriya Yoga "param-para" tradition achieved in their lives.

It is a very rare, high standard which only a few have obtained.

In Yoga tradition, a sanyasi who has achieved this "highest state of yoga" is recognized as a "Paramahamsa" and a householder who has achieved this state is known as a "Brahmarshi".

A "Kriya Yogacharya" is a teacher of Kriya Yoga, empowered by a Satguru of the "param-para" lineage of Kriya Yoga masters, (or another Yogacharya authorized to empower other yogacharya's), to give diksha initiation, and teach and guide students, on behalf of, and with the holy love, and blessings of their Guru.

A Yogacharya can be either a sanyasi or householder."

In seeking a Kriya Yoga master, one should be very careful.

Baba Hariharananda would often teach:

"Not all hills have diamonds, sapphires and rubies."

"Many are licking the outside of the coconut, saying how sweet the fruit inside tastes, but they have not tasted the sweetness of the fruit within" 

Samadhi Master Swami Hariharananda Giri

Definition from Yogapedia: What does Satguru mean?

Satguru, or sadguru, is the title given to one whose life purpose is enlightenment through Self-realization of the ultimate Truth.

The literal Sanskrit translation is “the true guru.”

A Satguru is an extreme rarity.

Characteristics of a Satguru are much different than those of a guru.

A guru is acquainted with his/her own personal truth, whereas the Satguru has realized the Supreme Truth.

Yogapedia further explains: Satguru

One that is beyond duality remains unaffected by abuse or pleasure and lacks all other contingent attributes that may distract from enlightenment.

The guru who is free from duality is a Satguru.

The Satguru is aware of the absolute Truth, which is comprised of all fathomable truths.

He is the preacher of all fundamental secrets and teacher of true Self-realization.

A Satguru is one who liberates us from suffering (through his/her example) and encourages direct contact with the Self.

Yogapedia Explains: Paramahamsa

In Vedic lore, the swan can distinguish between milk and water, even if they are mixed.

The swan, therefore, became a metaphor for enlightenment — the ability to discern the difference between what is real and what is not, even though they coexist.

It is this ability that indicates a sage has obtained moksha and is worthy of the title, Paramahansa.