GIA, the American gemological institute, holds a distinguished reputation as one of the diamond industry's most esteemed and precise laboratories.

Diamonds sourced from various regions across the globe are entrusted to the GIA institute for certification, wherein a comprehensive report is meticulously crafted, encompassing essential details such as diamond weight, color, clarity, and other pertinent characteristics.
Obtaining a certificate from this institute guarantees the acquisition of a superior diamond, having undergone thorough evaluation and grading by an impartial external gemological laboratory, ensuring accuracy and impartiality.
This certificate singularly reflects the true value of the purchased diamond, offering an unparalleled assurance of quality.
To safeguard against counterfeiting, each certificate bears a unique identification number, meticulously engraved on the stone itself.
As a testament to our commitment to excellence, every diamond surpassing half a carat in weight procured from our company will be accompanied by a certificate from the esteemed GIA, the epitome of gemological institutes.Since all the other certificates upgrade the colors and cleanliness of the diamonds After all, these certificates are hardly ever traded on the stock exchange and their price is between 30%-70% less than a GIA certificate. A customer looking for value always prefers a GIA certificate. 

For example: 

A 0.5 carat H color SI1 clarity diamond in good work without fluorescence with GIA certificate costs $1500 (The number is for illustration only). The same diamond with an Israeli gemological certificate was sold for 50% less, that is $750. Let's say the jewelry store's profit margin is 50%. According to these data, the diamond with GIA was supposed to be sold for $2250, while the diamond with the Israeli certificate was supposed to be sold for $1125.

But this is not the case! In practice, the jewelry stores sell the Israeli certificate for $1750 and convince the customer that a GIA certificate is too expensive and not worth buying. If the customer buys GIA, he pays a premium of $750 (2250-1500) and remains with a quality diamond. If the customer buys an Israeli certificate, he pays a premium of $1000 (750-1750) and is left with an inferior diamond. 

conclusion: If it is important for you to know the true value of the diamond you purchased, it is recommended to buy a diamond with a GIA certificate only.