One Bible verse that helps us answer your question is 1 Peter 3:3-4:  "Let not yours be

[merely] external adorning withthe wearing of jewelry…But let it be the inward adorning and beauty of the hidden person of the heartwith the incorruptible and unfading charm of a  gentle and peaceful spiritwhich is precious in the sight of God."  [Amplified Bible]

The Amplified Bible suggests that there is not an absolute rule about wearing jewelry.  If some churches, as you suggest, do not allow the wearing of jewelry, this would be a rule made by men.  There is no rule given by Jesus or the Apostles that says we cannot wear jewelry.

The Bible verse above does say that wearing jewelry is not valuable to our Heavenly Father.  He is looking at our heart.  Do we have a "gentle and peaceful spirit?"  We want to put our time and energy into things that help us grow inside, not outside.  Galatians 5:22-23 lists more of these  qualities that show we have grown into being more like Christ:  "love, joy, peace, patience, gentleness, goodness, faith, meekness, self-control.

The apostle Paul also tells us that those who are like Christ, and who have these qualities should:

  • "…be an example of the believersin conduct…" 1 Timothy 4:12.  Good conduct means that we would not wear expensive jewelry to show off. 
  • "[be]…teachers of good things."  Titus 2:3.  We should lift others to the highest goals in Christian life and not put our energy into outward show. We want to have spiritual qualities that are seen and followed by those younger in the faith.  

The inner "inner person of the heart" is what is important and it is what God values.  Why? Because the Lord is looking for Christians who have proven they have a character that has the "incorruptible" [eternal] qualities He is looking for. His faithful saints, who have the fruits of the spirit, will live forever and reign with Christ in heaven.