The most important thing every engaged couple needs is an engagement band.  Most will purchase a  large diamond, gold or platinum wedding band. Of course what an individual considers large depends upon what they have seen and what their friends have. When I sold diamonds the general public in my area would consider a 1.5 carat diamond large and three carat massive. 

If I went to a jewelry store only sixty miles away the clients shopping at that store would consider the three carat an average size diamond and 10 carat large. Now the cost of any quality diamond over 6 carats can be over $100,000. You would assume that any diamond in that price would have an independent grading report if not two to guaranty the quality. 

This store did not have any reports and they were excellent at selling but did not have much awareness of the standard of the product being sold.  What this usually means was that the buyer got a nice looking diamond that was just a bit under the grade said.  It is a  fine line between a VS1 and a VS2 so why get too fastidious.  Of course all is fine for few years til she finds the guy cheating with his office assistant. Now the diamond is up for sale and the purchaser looks at it and tells her it is only a Si 1 stone. She purchased it as a better quality VS1 and a better color than the buyer thinks it is. 

Now with a value difference of thousand they are off to court.  This is the same that occurs everyday with diamonds. Usually average size diamonds that average people can purchase. They assume that are as stated but don’t have independent documents to back up the grades. 

If you are buying a good size diamond you owe it to yourself to see only diamonds possessing an independent grading report.  When you compare you need to compare the same make of report to itself.  In other words GIA to GIA, ELG to EGL and IGI to IGI as eash has marginally different standards and quality control. Doing this will help you get the price you are expecting out of your diamond purchase. 

When you are ready to mount the diamond into a ring be certain to utilize a platinum head.  A platinum  wedding band or platinum mounting will hold the stone tighter and is less sure to crack or have prongs break off when hit.  Broken spikes make allowance for diamonds to pop out and bent prongs typically enable you time to see the issue and have it fixed before the stone is lost.Also remember to take a good quality photo or hire a professional commercial photographer to take a image for insurance. A photo will help replace a ring that may need to be custom made in the future.