simply stated

it is the diamond
that cuts through delusion

and this is a lofty claim
to cut through delusion

the diamond sutra is an ancient text
written in sanskrit
an even more ancient language
also known as
the vajra sutra

you can read it online if you search
there are pictures of gods
some guy known as the buddha
pages and pages of preamble and commentary
maybe 50 pages in you get to the sutra

apparently there are six requirements:

belief, hearing, time, host, and audience

if you are reading this
the requirements are met

you have to get through a lot of preamble
begging bowls and disciples and customs

there are a number of great quotes later in the text:

“They are neither dharmas nor no dharmas.
And why?
Unconditioned dharmas distinguish worthy sages.”

“There is no mark of self,
And no mark of others,
No mark of living beings
And no mark of a life.”

“All conditioned beliefs
Are like dreams.
illusions, bubbles, shadows,
Like dew drops and a lightning flash.”

“If you can have no thought,
you are not attached anywhere.
If you can have no thought,
you can produce that heart
without dwelling anywhere.”

what is the core essence of the diamond sutra?

dwell in the heart
think no thoughts
but there are no thoughts
this is why they are named no thoughts