Not necessarily. Many wedding rings especially Gold ring gets
worn out after many years so when they happen, it might be time to
replace it. You can renew your wedding vow when you do that.
FYI,
Diamond ring is an engagement ring. Traditionally (western
tradition), the guy should spend 3 months of his wage on the
diamond ring. Anyway, I don't think many guys follow that
tradition. Most of them just get what they can afford.
When picking for your diamond ring, you don't have to pick the one
with big stone. Best to try it on and see how well the size goes
with your finger. If you have slim finger, a big rock will stick
out like anything. Also, if you buy a diamond ring that is worth
over $10k, will you wear it everyday? You'll spend most of your
time worry about losing it. So, try to take that into
consideration. 0.5 - 1 carat will be the common size.
As for the wedding bands, the man should pick one with less Gold in
it (9K) since they do a lot of rough works, the ring with less Gold
will be stronger and less likely to get deformed. Female on the
other hand, can get one with more Gold (18K or more).
If you have 2 separate rings (engagement and wedding), the wedding
band should be worn "closer to the heart" (on the ring finger
between your knuckle and diamond ring). If you are considering to
have 2 rings, you'll need to make sure your wedding band goes well
with your engagement ring.
Hope the information helps! 
*Also, can you pm me your email add? So I can send you the order of
service etc*
