Step 1: Develop an Interesting Premise
For my prank, I decided to take something most folks value (diamonds) and invent a way for nearly anyone to make them. The idea being that even those folks who dont usually dabble in advanced chemistry might be interested in seeing how diamond could be made cheaply.
Step 2: Come Up With a (semi) Plausible Overall Explanation
After reading Rory Earnshaw's PopSci article "Smelting in a Microwave", I knew I wanted to incorporate a microwave oven into my story. I was pleasantly surprised when Wikipedia revealed that chemical vapor deposition is a method of growing diamond involving microwaves - SCORE!
Step 3: Add One or Two Small, Quirky Element to the Process
In my prank, I introduced the idea of adding olive oil to one small section of the graphite as the "secret" to making diamonds in a microwave. I further established that the olive oil should be applied via 100% cotton thread - as this could possibly make-or-break the whole process.
Step 4: Keep It Simple
Being fascinated by the announcement last year that scientists had discovered a way to generate x-rays by peeling scotch tape in a vacuum, I tried to justify adding a step in my fake-diamond-making-process that required x-rays. But in the end, I felt it would add too much complexity to the project. Not to mention, it'd be hard to create a plausible justification for it.
Step 5: Don't Be Offensive
In my story, I was able to generate a human interest angle - my 10th wedding anniversary. That part of the story was true. It was also somewhat serendipidis that a) the modern 10th anniversary gift is diamond jewelry, and b) the diamond is April's birth stone. However, my anniversary isn't April 1st... it's the 10th. (And, yes, I did get her something besides this "diamond" pendant.
Step 6: Take Good Photos
Everything in my photos is 100% real. It's my explanations of what's in the photos that's fake. I did use oil on the thread; but the thread wasn't 100% cotton. I did nuke the graphite in my microwave; but only for about 10 seconds (and it ARCED LIKE CRAZY). There was a lump of carbon left over; but it was overcooked angel hair pasta, not diamond. I really did make the pendant in the last step; but it was just a crumb of burnt pizza crust encased in epoxy.
Step 7: Be Mindful of Time-Zones
This is my one (admittedly minor) error. I didn't realize until after posting that Instructables uses "Left Coast" time. As such, my publish date is about 3 hours too soon. I did go back and make a few edits after the original posting that changed the edit date. But my original entry will forever be tagged as "published: Mar 31, 2009" - oh well.
Step 8: Manage the Comments
There are 3 types of comments: uncomplimentary, complimentary, and irrelevant. You can't control the first type, but you can add a few of the other two to dilute the effect of the first. I seeded my comments with 1 supportive and 1 irrelevant comment from friends, just to get things started.
Don't Get into an Argument
The more technical your subject matter, the more likely someone's going to "prove" you wrong. You'll be tempted to reply to their comments with a well thought-out counter-argument. But it probably won't help. Silence is usually the best reply.
Bury Their Comments Instead
Keep in mind: someone trying to expose your well-crafted prank has already made up their mind , and you won't change it. But you can lessen the chance that their comment will influence the next reader by burying it.
Because Instructables display the most recent comments first, adding a new comment to an existing thread will jump that entire thread to the top. This way, one well-placed (even irrelevant) comment by you could push an unsavory recent comment pretty far down the list.
Step 9: Don't Take It Too Seriously
For me, I take comfort knowing that for a short time, as many as 7,000 people lived in a magical world where it was possible to make a diamond in your microwave... and I made that possible.